HU207746B - Process for producing foamed polyisocyanate-polysilicic acid based party-compositions - Google Patents

Abstract

Combined polyisocyanate -polysilicic acid foam systems are prepd. from polyisocyanates and/or polyisocyanate prepolymers and/or polyurethane prepolymers. Based on isocyanate content 0.01-10 wt.% of amine type catalyst, foam stabiliser is also present, as well as in this case max. 70 wt.% fillers (based on total compsn.) are also included. Based on isocyanates 2-20 wt.% of a 20-60% solids contg. aq. alkali silicate soln. is added to above; (Me2O:SiO2 ratio values 0.2-0.4) and/or an aq. silicic acid sol soln. (of 10-50% solids) is used for the reaction. - Reaction between polyisocyanate and polysilicic-acid based components is carried out in the presence of two different types water soluble, water or alkali hydrolysable esters, either singly or mixed. (a) the B.pt. of an ester (or ester mixt.), or of alcohols liberated from them ranges from 50 deg. C to 150 deg. C. This constituent is used at a 1-30 wt.% level (based on silicate component); (b) the other ester is prepd. from a 2-6C polyol or ether alcohol acid from aliphatic carboxylic acids and/or boric acid. The B.pt. of these complete ester or ester mixts. is at a min. of 150 deg. C. This constituent is used at 1-50 wt.% (based on silicate component)

Description

The present invention relates to a process for the preparation of foamed polyisocyanate-polysilicic acid based systems by reacting isocyanate-containing compounds with an aqueous alkali metal silicate solution and / or aqueous silica sol in the presence of a catalyst and a foam stabilizer.

Systems known as "inorganic-organic plastics", known as "inorganic-organic plastics", are known to form systems associated with isocyanate-containing compounds (polyisocyanates and / or isocyanate-terminated polyisocyanate or polyurethane prepolymers) and alkali metal silicates or silica sols. they are typically high strength and sufficiently elastic, but at the same time have good thermal stability for the inorganic component and are substantially less flammable than polyurethanes.

No. 169,478. According to a solution disclosed in Hungarian Patent Application, the aqueous solution of alkali metal silicates and / or aqueous silicic acid salts are reacted with organic prepolymers having a reactive group capable of polyaddition and / or polymerization, which are predominantly polyurethane groups, or nonionic hydrophilic groups. The reaction is optionally carried out in the presence of various additives, such as fillers, inert solvents, activators, stabilizers and / or emulsifiers. No. 169478. polyurethane prepolymers for use according to Hungarian patent application (i) polyurethanes containing from 2 to 200 milliequivalents of ionic groups (preferably sulfonate or ammonium groups) and end-isocyanate groups per 100 g of prepolymer or (ii) mono- or polyhydroxy polyethers containing ethylene oxide polyurethanes containing nonionic, terminated isocyanate groups.

In addition to the polyurethane prepolymers, polyisocyanate prepolymers in which the monomeric units are linked by uretdione, isocyanurate, carbodiimide, allophanate, biuret and urea groups, and combinations of these and urethane groups, and at least the ionic or nonionic hydrophilic groups, containing two isocyanate groups, r. The terms "polyurethane prepolymer" and "polyisocyanate prepolymer" are used herein, and all polyisocyanates and polyisocyanate adducts which do not contain ionic or non-ionic hydrophilic groups, or in the above proportions and composition, are referred to as "polyisocyanates". The generic term "isocyanate component" is understood to mean polyisocyanates, polyurethane prepolymers and polyisocyanate prepolymers.

No. 169478. A special class of additives which can be used according to the Hungarian patent are boiling point -25 ° C to + 50 ° C, which are used as propellants in the formation of the foamed product. The most widely used types of propellants are halogenated alkanes (such as methylene chloride, chloroform, ethylidene chloride, vinylidene chloride, monofluorotrichloromethane, chlorodifluoromethane, dichlorodifluoromethane) which are known to cause environmental pollution. Other volatile organic liquids, such as lower alkanoic carboxylic acid monoesters, lower alcohols, lower ketones, ethers and alkanes (such as butane, hexane and heptane), which are known to be flammable or harmful to health, are also used as propellants. their use is detrimental to safety and health.

No. 3,981,831. U.S. Pat. to form polyisocyanate-polysilicic acid based systems by reaction of C 1-9 organic compounds having from 32 to 400 molar masses containing additional hydrophilic and / or polar groups). The organic compound containing the hydrophilic group facilitates the homogenization of the isocyanate compound forming the organic component of the coupled system and the aqueous solution constituting the inorganic component, thereby enabling the formation of an aqueous sol containing a very finely divided disperse phase and increasing number of inorganic groups. However, some of the hydrophilic group compounds themselves are involved in the reaction and modify the properties of the product formed. No. 3 981831. For example, U.S. Pat. No. 4,129,629 discloses hydrophilic organic compounds as alcohols, thiols, phenols, thiophenols, halogenated alkanes, nitriles, esters, ethers, thioethers, ketones, nitro compounds, carboxylic acids, sulfonic acids, carboxylic and sulfonic acid halides, aldehydes. As esters, the cited citation refers only to monocarboxylic acids of monohydric alcohols (containing one hydroxy group). Provided that no. U.S. Patent No. 5,123,198, which is intended to produce foamed articles by adding propellants to the reaction mixture; these are the same as those described in U.S. Patent No. 169,478. and the same drawbacks. No. 3 981831. In some cases, U.S. Patent No. 4,800,500 discloses sufficient foaming of a product without an organic additive containing a hydrophilic group.

Although carbon dioxide is released during the reaction between the isocyanate group and the water and the alkaline silicate solution, which could in principle fulfill the function of a blowing agent, carbon dioxide is not sufficiently utilized for foaming. In either case, the rate of carbon release cannot be controlled or coordinated with the other partial reactions. At first slowly, then

EN 207 746 Β carbon dioxide, which is liberated more and more vigorously as the reaction progresses, results in uneven bubble formation, uncontrolled cellular structure, which results in degradation of product quality and, in extreme cases, inability to produce a reproducible product. Therefore, one of the objectives of the cited publications is the partial or total removal of carbon dioxide from the system, which is achieved by absorbing or sequestering carbon dioxide at the rate of its development in water or in an alkaline silica solution.

Hungarian Patent No. 199527 discloses a solution for the preparation of foamed polyurethane-polysilicic acid-based composite systems utilizing the carbon dioxide evolved in the reaction as the blowing agent, thereby eliminating the disadvantages of previously used blowing agents (environmental pollution, fire hazards, health hazards). In the process described therein, the amount of polyisocyanate and water glass are adjusted to a ratio such that the ratio -NCO / Me ₂ O (Me represents an alkali metal) is greater than 2 and the reaction is carried out in the presence of a special hydrophobic polysiloxane-polyether block copolymer. By adjusting the A-NCO / Me ₂ O ratio and using the hydrophobic polysiloxane-polyether block copolymer, they control the smooth fine dispersion of carbon dioxide, while the hydrophobic polysiloxane-polyether block copolymer stabilizes the cellular structure of the foam.

However, this solution has the disadvantage that it can only be used in a relatively narrow range (colloidal silica sols are not at all used as reagents and will also give satisfactory results when alkali metal silicates are used as reagent only if the -NCO / Me2 ratio in the reagent mixture exceeds 2: 1). A further disadvantage is that the hydrophobic polysiloxane-polyether block copolymer used to stabilize the foam structure often does not optimize the quality of the product due to the fact that the cellular structure of the foam material (and consequently its thermal and mechanical strength) is not as well controlled well known blowing agents are used instead of or in addition to carbon dioxide.

In the course of our work, we have set out to remedy these shortcomings.

It has been found that the carbon formed during the reaction of the isocyanate groups can be made directly suitable for foaming in a wide variety of foamed polyisocyanate-based polysilicic acid based systems, thereby avoiding the disadvantages of using blowing agents, while maintaining the cellular structure of the foam in addition to reagents, catalyst and foam stabilizer, two different types of water-soluble esters which are hydrolyzable with water or aqueous alkaline solution,

- the boiling point of one of the esters or of the alcohol liberated by hydrolysis is between 50 and 150 ° C,

and the other ester is a total ester of a polyol or ether alcohol containing from 2 to 6 hydroxy groups and having a boiling point of at least 150 ° C with C 1 -C 4 aliphatic carboxylic acids and / or boric acid.

According to the invention, both ester components can also be used in the form of mixtures of esters of the respective type.

The present invention relates to a process for the preparation of a foamed polyisocyanate-polysilicic acid-based composite system, wherein the polyisocyanate and / or polyisocyanate prepolymer and / or polyurethane prepolymer is present in an amount of 0.01-10% by weight of the isocyanate component, foam stabilizer and optionally in the presence of up to 70% by weight, based on the total weight of the composition, of 20 to 60% by weight of an aqueous alkali metal silicate solution (wherein the ratio Me ₂ O / SiO ₂ is between 0.2 and 4) and / or 10-50% by weight aqueous silica sol. According to the present invention, the reaction is carried out in the presence of two different types of water-soluble ester which can be hydrolyzed with water or an aqueous alkaline solution, or a mixture thereof, wherein

- one of the esters (or mixtures of esters) or the alcohol degree released during hydrolysis has a boiling point in the range of 50-150 ° C and is present in an amount of 1-20% by weight, preferably 2-10% by weight, of the silicate component, and

- the total ester of the other ester with 2 to 6 hydroxy groups of a polyol or ether alcohol having a boiling point of at least 150 ° C with aliphatic carboxylic acids and / or boric acid and having from 1 to 50% by weight of the silicate component is present in an amount of from 5% to 30% by weight.

Some representative polyisocyanates and polyisocyanate prepolymers useful in the process of the present invention are disclosed in U.S. Pat. listed in U.S. Pat. Among the prepolymers which can be used in the process of the invention, the polyurethane types are the same as those described in U.S. Pat. as described in the Hungarian patent. These prepolymers are disclosed in U.S. Patent No. 169,478. can be prepared according to the procedure disclosed in Hungarian Patent Specification. Polyisocyanate prepolymers may be prepared in a manner similar to polyurethane prepolymers.

Organic compounds containing primary, secondary or tertiary amino groups as amine-type catalysts in the reaction, e.g. and 199527. The materials listed in Hungarian patents which are known catalysts for the production of polyurethane can be used.

As aqueous alkali metal silicate solutions and aqueous silica sols, see U.S. Patent No. 169,478. Hungarian Patent No. 3,988,183. U.S. Pat. Any of the materials described in the Hungarian patent can be used. These are referred to hereinafter as the "silicate component".

As foam stabilizers in the reaction, for example, 199,527

HU 207 746 Β Polysiloxane-polyether block copolymers described in Hungarian Patent Application No. 6,198,198 to Kunststoff Handbuch (Vieweg und Höchtlen, Cari Hauser Verlag, Munich, 1966). Volumes 103-113. and U.S. Patent No. 3,629,308. foam-stable isomers listed in U.S. Pat. They may preferably be present in an amount of from 0.1 to 10% by weight based on the total weight of the foam.

The reaction mixture may optionally contain fillers in an amount of up to 70% by weight, preferably 0 to 50% by weight, of the total composition. As fillers, any of the fillers listed in the previously cited publications may be used. The filler may alter some of the product properties, such as increased adhesion, reduced flammability, etc.

According to the invention, the boiling ester (or alcohol providing such a boiling point) of 50-150 ° C in the reaction mixture is, for example, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, ethyl formate, npropyl formate, isopropyl formate, methyl acrylate, ethyl acrylate, trimethyl borate, trimethyl phosphate, triethyl borate, triethyl phosphate, tetra (C 1-4 alkoxy) silane and the like. may. These esters, or mixtures thereof, are hereinafter referred to as "low-boiling esters".

The total ester of the polyol or ether alcohol containing 2-6 hydroxy groups used in the reaction mixture is, for example, ethylene glycol diformate, ethylene glycol diacetate, propylene glycol diacetate, diethylene glycol diacetate, triethylene glycol diacetate, polyethylene glycol. (200) diacetate, glycerol triacetate, trimethylolpropane triacetate, glycerol tripropionate, boric acid glycerol complex and the like. or a mixture thereof. By "total ester" is meant that all hydroxyl groups of the polyol are linked with an esterification group. These esters, or mixtures thereof, are hereinafter referred to as "polyol esters".

In the process of the invention, the foaming occurs as a result of a series of partially parallel reactions by essentially the following mechanism:

During the reaction of the isocyanate component with the silicate component, the organic-inorganic polymer backbone is gradually formed and simultaneously carbon dioxide is released. In parallel with the release of carbon dioxide, the low boiling ester or the alcohol liberated by its hydrolysis is converted into vapor and these vapors are involved in foaming. The alcohol released from the low-boiling ester reacts with the -NCO groups of the isocyanate component, and the acid component of the ester is converted to a salt and entrapped in the gel matrix so that these components are incorporated into the product and do not lead to release of contaminants. As the reaction proceeds, the hydrolysis of the polyol esters also begins. The resulting polyols react with their reactive hydroxyl groups with the -NCO groups of the isocyanate component and are chemically incorporated into the product. Unlike the monofunctional alcohols liberated from the low spinning esters, polyols do not exert a chain-closing action because they still have groups carrying the polymerization. The foam stabilizing effect of the polyol esters may be explained by the presence of groups carrying the polymerization and the viscosity controlling effect of the compounds. As a result of all these sub-processes, carbon dioxide, low-boiling ester and the alcohol formed therefrom are utilized as blowing agents in the formation of the foam structure; and the polyol ester, together with the foam stabilizer present, stabilizes the cellular structure of the foam and improves the elasticity of the cell walls. By varying the amount and quality (particularly the boiling point and reactivity) of the low-boiling ester and the polyol ester, the degree of foaming and cellular structure can be finely controlled as is known in the art using auxiliary blowing agents.

The invention is further illustrated by the following non-limiting Examples.

Example 1

No. 169478. A polyurethane prepolymer containing inter-chain sulfonate groups and end-isocyanate groups is prepared as follows:

1800 g of technical grade 4,4'-diphenylmethane diisocyanate are mixed with 200 g of trimethylol propane-initiated 250 hydroxyl polyethylene glycol at room temperature. This gives a prepolymer having an NCO content of 25.6% by weight and a viscosity at 25 ° C of 1960 cP. This prepolymer was dissolved in 1000 g of 1,2-dichloroethane and a solution of 144.5 g of sulfur trioxide in 1,2-dichloroethane (33.3% by weight) was added dropwise over 90 minutes. After stirring at 70 ° C for 1 hour, the excess 1,2-dichloroethane was distilled off and the residue was cooled. The product obtained had a viscosity of 7500 cP at 25 ° C, a sulfur content of 0.85 wt%, and an NCO content of 26 wt%.

To the resulting polyurethane prepolymer (g) was added 60 g of technical grade polyisocyanate having a viscosity of 400 cP at 20 ° C (see Example 2), 40 g of propylene glycol diacetate, 10 g of ethyl acetate and 2 g of polysiloxane polyether. After homogenization, a mixture of 170 g of concentrated (34% w / w) aqueous sodium water glass solution and 10 g of oleic acid in diethylamine was added. Stir the mixture for 20 seconds with a high speed stirrer, then stop stirring. The foam formed is approx. It reaches its full height after 90 seconds. After 1 hour, the hard foam formed is removed and the mechanical properties examined. The foam has a bulk density of 120 kg / m ³ . The foam has a compressive strength of 10% at room temperature and 40% higher at 120 ° C from a polyurethane having the same volume of 4,4'-diphenylmethane diisocyanate and 250 hydroxyl polyethylene glycol inactivated by trimethylolpropane (material used for prepolymerization). hard foam strength.

Example 2

No. 169478. A polyurethane prepolymer having inter-chain ethylene oxide groups and an isocyanate end group is prepared as follows:

HU 207 746 Β

From the crude phosgenated product of the aniline formaldehyde condensate, distillate an amount of diisocyanato-diphenylmethane such that the viscosity of the distillation residue at 25 is 400 cP. 80 kg of the thus obtained distillation residue (proportion of 2-condensed ring compounds 45.1%, proportion of 3-condensed ring compounds 22.3%, more than 3% of condensed ring compounds 32.6%, NCO content: 30- 31 kg by weight) was mixed with 16 kg of n-butanol-initiated polyethylene oxide mono-alcohol and the mixture was heated at 80 ° C for 8 hours. The prepolymer thus obtained had an NCO content of 24.6% by weight and a viscosity of 25 ° C at 300cP.

To 150 g of the thus obtained polyurethane prepolymer are added 50 g of a starting polyisocyanate having a viscosity of 400 cP (the same as the distillation residue above), 50 g of glycerol triacetate, 10 g of methyl acetate and 5 g of polysiloxane polyether. Aqueous solution of water in a dry solids solution (Na ₂ O / SiO ₂ ratio 1: 2) and 5 g of triethylene diamine catalyst. The mixture is stirred for 10-20 seconds. The procedure of Example 1 is then followed. The foam obtained had a bulk density of 25 kg / m ³ and a hot flexural strength of 131 ° C.

Example 3

To a mixture of 450 g of the polyurethane prepolymer prepared as in Example 2, 100 g of ethylene glycol diacetate and 30 g of tetraethoxysilane was added 450 g of sodium water glass (dry weight 44%, Na ₂ O / SiO ₂ ratio 1). 2), 5 g of amine catalyst (75% by weight, Ν, Ν-dimethylaminoethane and 25% by weight of diazabicyclooctane) and 4 g of polysiloxane-polyether are added. The reaction mixture was stirred vigorously for 15 seconds in a fast mixer and then poured into a paper bag. After the foaming is complete and the product has cooled, the articles are removed from the paper bag and mechanical properties are determined. (For comparison, the mechanical data of a foam containing 60 g of trichlorofluoromethane instead of ethylene glycol diacetate and tetraethoxysilane is shown in parentheses, which corresponds to Example 10 of Hungarian Patent No. 169,478. ) bulk density: 17 kg / m ³ (15 kg / m ³ ) compression strength: 0.55 kp / cm ² (0.22 kp / cm ² ) change in volume over 5 hours at 180 ° C: 0% (0 %) open cells ratio: 93% (97%) snow conductivity number: 0.037 kcal / mh grd (0.035 kcal / mh grd) flammability according to ASTM D 1692-68: SE (SE) = self-extinguishing hot flexural strength: 138 ° C (119 ° C) ).

Claims (5)

A process for the preparation of a foamed polyisocyanate-polysilicic acid-based composite system, wherein said polyisocyanate and / or polyisocyanate prepolymer and / or polyurethane prepolymer is present in an amount of 0.01 to 10% by weight based on the isocyanate component amount of the amine catalyst, foam stabilizer and optionally in the presence of up to 70% by weight, based on the amount of filler, of 20 to 200% by weight of an aqueous alkali metal silicate solution (wherein the Me ₂ O / SiO ₂ ratio is between 0.2 and 4) and / or 1050% by weight of the isocyanate component. with an aqueous silica sol, wherein the reaction is carried out in the presence of two different types of water-soluble esters which can be hydrolyzed with water or an alkaline solution, or a mixture thereof, wherein (a) one ester (or mixture of esters) or the alcohol (s) liberated during hydrolysis has a melting point in the range of 50-150 ° C and is used in an amount of 1-20% by weight of the silicate component, and (b) the total ester of the other ester with a polyol or ether alcohol containing from 2 to 6 hydroxy groups, having a boiling point of at least 150 ° C with C 1 -C 4 aliphatic carboxylic acids and / or boric acid, and 1 to 50 parts by weight of this component; by weight. The process according to claim 1, wherein the ester of type a) is used in an amount of 2 to 10% by weight, based on the silicate component. The process according to claim 1 or 2, wherein the ester of type b) is used in an amount of 5 to 30% by weight, based on the silicate component. 4. Process according to any one of claims 1 to 3, characterized in that the esters of type a) are methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, ethyl formate, n-propyl formate, isopropyl formate, methyl acrylate, ethyl acrylate, trimethyl borate, trimethyl phosphate, triethyl borate, triethyl phosphate, tetra (C1-C4 alkoxy) silane, or mixtures thereof. 5. A process according to any one of claims 1 to 5, wherein the ester of type b) is ethylene glycol diformate, ethylene glycol diacetate, propylene glycol diacetate, diethylene glycol diacetate, triethylene glycol diacetate, polyethylene glycol ( 200) diacetate, glycerol triacetate, trimethylolpropane triacetate, glycerol tripropionate, boric acid glycerol complex, or mixtures thereof.