WO1998016576A1 - Binding agent composition - Google Patents

Abstract

In order to produce a solid foam structure the use of a composition with a binding agent is recommended. Said composition contains an elastically compressible filler material instead of a propellant gas. The result is an environmentally friendly and easy means of coating, gluing, sealing or filling using foamed structures. Said composition is particularly useful when used as in-situ foam for assembly purposes.

Description

 "Binder composition"

The invention relates to a binder composition for coating, gluing, sealing, insulating and filling with the formation of a foam structure, and the production and use thereof.

Local polyurethane foams are used for a number of construction applications. Here are one-component foam systems which contain a mixture or solution of a moisture-curing NCO prepolymer - preferably based on MDI - and a propellant gas liquefied under pressure, e.g. PFC 1 52a, PFC 1 34a, DME or propane / butane are dominant. Such assembly foams, also known as “frothing foams”, expand spontaneously immediately after removal from the pressure container, for example an aerosol can, by evaporation of the dissolved and / or emulsified propellants. Therefore, these foam systems can also be used in vertical joints where other systems, for example two-component systems from cartridges fail due to their flow behavior or only result in a slight gap bridging (max. 1 0 mm).

A particular disadvantage of PU foams made from aerosol cans is their propellant gas content. The halogen alkanes must be viewed critically because of their global warming potential. With a Greenhouse Warming Potential (GWP) of 0.26, FKW-1 34a still has around a quarter of the global warming potential of the fully halogenated CFC-1 1 product (GWP = 1, 0). Other fluoroalkanes like FKW-1 52a are flammable and still have a noticeable GWP of 0.02. The hydrocarbons, eg propane / butane, and dimethyl ether have no global warming potential; their degradation in the lower atmosphere contributes to photochemical smog. Therefore, these propellants are not fully environmentally friendly. Another disadvantage of the assembly foams with propellant gases can be seen in the pressure container used, which always represents a safety risk, albeit a small one.

There is therefore a need for foaming systems that can be used without the use of disposable pressure containers, e.g. Aerosol cans are applicable. Foaming NCO prepolymers without propellant gases and without pressure vessels are described in some patent applications. For example, EP 1 25 582 describes an NCO prepolymer for gluing building parts which contains 10 to 20% of a fully halogenated solvent with a boiling temperature of 20 to 60 ° C. The bulk density of the foams obtained is more than 200 g / l. In addition to the high bulk density, there are other disadvantages. For example, the liquid prepolymers can only be foamed on horizontal or slightly inclined surfaces. In DE 39 41 595, a liquid NCO prepolymer is injected into an open-cell soft foam provided with channels and openings, which is previously mechanically pressed into a vertical joint. The foam obtained in this way has good adhesive properties, but because of the cumbersome processing, this problem solution is not satisfactory.

All of the problem solutions described, which lead to foaming without a pressure vessel, have in common that a moisture-curing NCO prepolymer is used which releases carbon dioxide by reaction with atmospheric or ambient moisture, which is the actual propellant gas for the foam formation or expansion of the prepolymer.

Building on this prior art, the task arose to find a composition which, without gas formation, gives a foam which can easily be used for coating, gluing, sealing, insulating and filling.

The solution according to the invention can be found in the patent claims. It is based essentially on the use of elastic compressible fillers in the binder. For example, foams are obtained if elastic particles of low density (<<1 g / ml) are compressed by a slight overpressure and in this compressed state are coated with any liquid, pasty, gel-like or even solid binder, so that preferably compressed hollow particles with a coating of binder is present. The flowable mixture thus obtained is poured into suitable containers, for example into cartridges, buckets or bags, and is introduced from these containers by pressing, for example into any cavities, preferably joints, where it hardens or sets after it has expanded. Instead of a blowing agent (gas or gas-forming substance), an elastic compressible filler is used in the binder.

The invention thus essentially consists of an informal binder composition for coating, gluing, sealing, insulating, filling with the formation of a foam structure under expansion, the binder containing at least one elastic compressible filler.

Hollow bodies made of polymers which have an elastic modulus of at least 0.5 N / mm ² at 0 to 50 ° C. are suitable as elastic compressible fillers.

The hollow bodies therefrom should be compressible by a factor of 1.5 to 100, preferably by a factor of 2 to 50, at an overpressure of up to 10 atmospheres, in particular from 0.05 to 5 atmospheres. In addition, such a compressed hollow body should also within a period of 0.1 to 120, in particular from, after a storage time of 6 months

Recover 0.5 to 60 min to at least 70 vol% of its volume if it expands after application.

The density of the hollow body should be at most 500 g / l, preferably _ < _^ 400 g / l, at atmospheric pressure.

Fillers of any shape can be used (granules).

Fillers which are obtained by comminuting open-cell or closed-cell soft or elastic foam plastics are particularly suitable. Multicellular hollow bodies are expediently used; Hollow balls are also possible. The particle size of the fillers should not exceed 20 mm after their expansion, preferably 1 to 10 mm and a minimum of 0.2 mm. Then the composition according to the invention still flows in most applications. In special cases, larger fillers can also be used, for example if a gap of more than 3 cm thick is to be sealed.

Any polymer can be used as the base material for the elastic compressible fillers, e.g. Soft PVC, soft polyurethanes, styrene-butadiene copolymers, vinyl acetate-ethylene copolymers, acrylic ester copolymers, natural rubber and silicone elastomers. In general, polymers and copolymers with a glass transition temperature <0 ° C, preferably -20 ° C to -55 ° C can be used.

Elastomers are expediently used, that is to say chemically or physically crosslinked plastics with rubber-elastic behavior. Specifically, the following are mentioned: ACM, AU, BHR, BR, CHR, CM, CO, CR, CSM, EAM, ECO, EPDM, S, EP (D) M, P, EU, EVM, FKM, FVMQ, H-NBR, HR, MVQ, NBR, NR (IR), OT, PNF, PnR, SBR, X-NBR). Preferred are: ACM, CO, ECO, FKM, FVMQ, H-NBR and PNF.

The elastically compressible filler is preferably an elastomer with an open-cell or closed-cell foam structure.

The base material for the elastic compressible filler can itself also be deformed more or less plastically if there is a closed-cell foam structure. E.g. a polystyrene foam compresses without the enclosed gas escaping, the filler recovers sufficiently due to the compressed gas.

"Binder" is understood to mean a substance or mixture of substances with which other substances of the same or different types can be combined with one another. The setting can take place physically by drying an aqueous or organic solution or dispersion or by solidifying a melt, or chemically by a reaction, for example by the action of moisture - preferably atmospheric humidity, atmospheric oxygen, UV light, short-wave visible light or by the action of Warmth. Solid binders must therefore be made liquid by adding water or organic substances. When used, the binder should have a viscosity of 1 00 to 1 0 ¹⁰ , in particular from 1 0 ³ to 1 0 ⁸ mPas at the application temperature, in particular between -50 and 300 ° C, preferably between 0 and 50 ° C. The binders can be of an inorganic nature, for example gypsum, cement, water glass and lime. However, preference is given to organic binders, as are usually used in adhesives and sealants, and in casting resins and coating compositions. Such binders are based, for example, on the following substances, in particular polymers: drying oils, alkyd resins, acrylic resins, polyisobutylene, polyvinyl ether, polyvinyl alcohol (as a solution), polyvinyl acetate, styrene-butadiene copolymers, styrene-acrylate dispersions, ethylene-vinyl acetate dispersions, polyurethane Dispersions, reactive

Polyurethanes, silicones, PA, PES, E / VA and P

Hotmelt adhesives are also expediently used as binders, in particular based on PA, PES, PU and E / VA.

Preferred binders are water-free and solvent-free reactive binders which lead to linear polymers or three-dimensionally crosslinked elastomers. Among these reactive systems, moisture-curing polyurethanes and atmospheric oxygen-crosslinking resins and systems crosslinking via silane groups (e.g. silicones, silane-terminated polyurethanes, alkoxysilane-terminated polyethers, etc.) are particularly preferred.

The reactive systems can be either one-component or two-component, it being possible for the expanding fillers to be present in one or in both components.

Among the moisture-curing polyurethanes are prepolymers of any polyols with aromatic diisocyanates, preferably TDI and MDI, with cycloaliphatic isocyanates, especially H 1 2MDI and IPDI and aliphatic diisocyanates, e.g. HDI, butane diisocyanate suitable.

Preferred polyols are diols, triols and mixtures thereof based on alkylene oxides - preferably EO and PO, particularly preferably mixed alkylene oxides - with a MW of 400 to 6000, preferably 900 to 4000 and a functionality between 2 and 3, furthermore oleochemical polyols O

Base, e.g. Soy polyols with OHZ from 1 20 to 220, castor oil with OHZ = 1 65 and their EO and / or PO adducts with OHZ 50 to 1 80.

In addition to the polyether polyols and oleochemical polyols, polyester polyols, preferably linear or slightly branched, can also be used to form the prepolymer. Polyester polyols composed of adipic acid, phthalic anhydride, diethylene glycol, triethylene glycol and neopentyl glycol are particularly preferred.

The weight ratio of filler to binder should be chosen so that the

Mixture can still be processed sufficiently when used, i.e. his

Viscosity should range from 10 ² to ^{10 10} mPas, especially from 10 ³ to

10 ⁸ mPas are between 0 and 50 ° C, measured according to Brookfield at

Application temperature.

In general, the weight ratio of binder to filler is 1:20 to 50: 1, in particular 1:10 to 20: 1.

In addition to the two essential components (elastically compressible filler and binder), there may of course be further components in the composition. The type and quantity of these are known from the known formulations for coating compositions, adhesives, casting compositions and filling compositions. These are in particular other fillers, plasticizers, solvents, anti-aging agents, dyes, flame retardants, etc.

The invention. Composition is made by mixing its components.

The composition according to the invention is applied under pressure, the pressure being able to be generated before storage or only during use. The low-pressure or unpressurized composition stored in a cartridge, for example, is first compressed more or less during use and pressed, for example, into a gap by a nozzle. The compressed fillers recover with an increase in volume before the binder sets. As a result, the gap is completely filled with a firm foam structure. However, the composition according to the invention is expediently stored under an excess pressure of up to 10 bar, in particular from 0.05 to 5 bar. For this purpose, the fillers are precompressed, for example, before they are incorporated into the binder, the excess pressure being 5, preferably up to 2 bar. A preferred form of incorporation is that the elastic hollow bodies are subjected to a vacuum, in particular in the case of closed-pore fillers, as a result of which the gas in closed-cell particles escapes by diffusion. If the particles are again exposed to the atomic pressure after their vacuum treatment, the particles shrink to a fraction of their original dimensions and can be wetted immediately afterwards with a liquid or liquid binder (e.g. a softened hot melt adhesive) and filled under light pressure e.g. in cartridges. This pressure is expediently chosen so that the shrunk hollow particles do not expand in the cartridge due to their elasticity, it being necessary in the case of cartridges to prevent the pistons from being pushed out and in the case of hot-melt adhesives to prevent the mass from expanding if the melt has not yet solidified is.

In this case the binder is used as a pressure vessel, i.e. the compressed filler particles are coated with a binder which is solid at room temperature, or completely or partially coated. The binder can e.g. be a hot melt adhesive. When used, it is liquefied by heating, and the filler can then expand. It is similar when using gypsum or water-soluble polymers as binders and water as softening agents. The form of this composition of compressed filler with the binder as a pressure vessel depends primarily on the application. For example, in the case of the hot-melt adhesive, a rod shape is expedient, and in the case of the gypsum, a free-flowing granulate shape.

Due to the simple handling and the propellant-free formation of foam structures, the composition according to the invention is suitable, for example, as a local foam for the assembly of doors and windows or for coating surfaces, for filling cavities and for insulating. In addition, gap-bridging bonds are easily possible, for example, wall cladding. Furthermore, upholstery etc. can also be carried out with such foams if an elastic component is also used as the binder.

The production of moldings with a foam structure is also simple if the composition according to the invention is pressed into a mold and the mold is removed after setting.

By selecting suitable components, such as Flame retardants, fire-resistant binders (e.g. silicones, gypsum) can be formulated into foams with a high fire resistance.

By using water-soluble binders, it is also possible to formulate water-soluble or washable foams.

The invention will now be explained in detail by means of examples.

Examples

1 . Production of the elastic micro hollow body

1 .1 PU soft foam granulate (G 1)

Made of a commercially available, open-cell, elastic soft foam

Bulk density 20 kg / m ³ was obtained by crushing in a cutting mill

(Thermomix, Vorwerk) produced a granulate, the following

Data has:

Particle size: 2 to 5 mm

Bulk weight: 1 5.0 g / l

The further processing of the granules will be described later.

1 .2 PU soft foam granulate (G2)

From a PU soft foam with a bulk density of approx. 30 g / l and an open cell content of <50%, made from a moisture-curing one-component system from pressure vessels, a granulate was produced by crushing as in Example 1 .1, which has the following data: particle size: 1.5 to 3.5 mm

Bulk weight: 26.0 g / l

1 .3 Cellular rubber granulate made of SBR and natural rubber (G3)

From a commercially available cellular rubber sheet type ZK / NRL from Kopp Zellkautschuk, Aachen with a bulk density of approx.

1 40 g / l were produced by crushing a granulate with different particle sizes:

Particle size: 3 to 5 mm

Bulk weight: 70 g / l

1 .4 Foamed granules made of polystyrene (comparative test) (GM)

A commercially available pre-expanded foam granulate VP-800 from BASF with the following data was used: Particle size: 0.5 to 2.0 mm

Bulk weight: 20 g / l

2. Binder 2.1 Binder B1: NCO prepolymer castor oil OHZ = 1 65 13.3% polyethylene glycol, MW = 600 13.3% tris (2-chloropropyl) phosphate 1 5.0% siloxane-oxyalkylene copolymer 1, 6% dimorpholinodiethyl ether 0.4 % Raw MDI / 31.0% NCO, F = 2.7) 56.4%

100.0%

Viscosity (25 ° C after Brookf. RVT): 1 2 800 mPas

2.2 Binder B2: Aqueous dispersion of a styrene-acrylic ester copolymer (B2)

Acronal 290 D, BASF 95.0%

Dicyclohexyl phthalate 5.0%

100.0%

Viscosity (25 ° C after Brookf. RVT): 5,000 mPas

3. Production of the foaming or pre-foamed mixtures From a granulate and a binder, a still flowable paste was produced in a vacuum mixer, which was filled into a plastic or aluminum cartridge under a slight pre-pressure. The ratio of binder / pre-compressed filler depends on the binder absorption and is listed in the table with the test results.

Testing of pastes made from pre-compressed foam granulate and binder:

In a space formed by two commercially available particle boards with a size of 1 00 x 200 x 1 9 mm, which were at a distance of 1 0 mm, the mixture of a binder and foam granulate filled into the cartridge was introduced by means of a commercial cartridge gun and im Standard climate (23 ° C / 50% rel. F.) your Curing by ambient moisture (in the case of the moisture-reactive binder B-1) or physical setting by evaporation of the water in polymer dispersions (binder B-2) awaited.

After setting / drying, the plates were separated and a representative piece was cut out of the irregular foam body obtained to determine the bulk density. The

Volume was determined by measuring the length, width and depth of the foam body. The bulk density can be obtained from its weight.

The foams obtained have the following properties:

Example No. 1 2 3 4 5 6 7 8

Binder B1 93 91 89 93 91 89 85 86 n-pentane 2 4 6 2 4 6 6

Foam granulate G 1 5 5 5

Foam granules G2 7.5 7.5 7.5

Foam granulate G3 1 5

Foam granules V1 8.0

Density of hybrid

Foam, g / l 480 300 235 220 1 35 80 1 30 1 90

Expansion at

Exit from the

Cartridge yes yes yes yes yes yes yes no

Claims

claims 1 . Binder composition for coating, gluing, sealing, insulating and filling to form a foam structure under expansion, characterized in that it A) a binder and B) contains at least one elastic compressible filler. 2. Composition according to claim 1, characterized in that the binder is an NCO prepolymer of at least one polyol and at least one polyisocyanate with an NCO / OH ratio of> 2/1, which has a viscosity of 1 to 50 Pas at 20 ° C to Brookfield. 3. Composition according to claim 1, characterized in that the binder is an aqueous or non-aqueous dispersion of a polymer or copolymer with a film-forming temperature of at least <5 ° C. 4. Composition according to claim 1, characterized in that the binder is a hot melt adhesive. 5. Composition according to claim 1, 2, 3 or 4, characterized in that the elastic compressible filler by a factor of 1, 5 to 1 00, preferably by a factor of 2 to 50 at an overpressure of up to 1 0 bar, in particular of Is compressible from 0.05 to 5 bar and recovers to at least 70% by volume of its volume within 0.1 to 120 minutes, in particular within 0.5 to 60 minutes, when there is no longer any excess pressure. 6. Composition according to at least one of the preceding claims, characterized in that the elastically compressible filler is an elastomer with a foam structure. 7. The composition according to claim 6, characterized in that the elastomer is a chemically or physically cross-linked plastic. 8. Composition according to at least one of the preceding claims, characterized in that it is liquid when used, ie a viscosity of 10 ² to 10 ¹⁰ , in particular 10 ³ to 10 ⁸ mPas at the application temperature, in particular between -50 and 300 ° C. , preferably 0 to 50 ° C. 9. Composition according to at least one of the preceding claims, characterized in that the composition is under an excess pressure of up to 10 bar, in particular from 0.05 to 5 bar at 0 to 50 ° C, in particular at 20 ° C. 1 0. A process for the preparation of the composition according to claim 8, characterized in that a) the elastically compressible filler is first compressed or degassed with a reduction in volume and b) the compressed filler is mixed with the binder under excess pressure and c) this mixed composition stored under pressure. 1 1. Use of the composition according to at least one of claims 1 to 9 for sealing, insulating, filling and gluing, in particular as local foam.