DE4211302A1 - Elastic, water-swellable joint sealing a materials - contain water- absorbent filler, e.g. polyacrylate salt or bentonite, in a hydrophilic polyurethane matrix - Google Patents

Abstract

Water-swellable sealing materials with rubber-like properties (I) contain knwon substances (II) which become very swollen in water, incorporated into a matrix which is obtd. by reaction of known hydrophilic isocyanate prepolymers (III) with chain extenders such as water, alcohols or amines (IV) in the ratio (III):(IV) of(1:9)-(9:1). Pref. (I) can be produced with a homogeneous solid, microporous or cellular foam structure. The following can also be added to modify the properties of (I) or to reduce shrinkage on drying: (a) known aq. dispersions or solns. of high polymers, (b) aq. emulsions of bitumen, asphalt, or tar, or combinations thereof with (a), with ratio (III): (a or b) = (1:9)-(9:1) or ()c) solid (in)organic fillers with definite particle size, or fibres and colour pigments, in amts. of 1-150% w.r.t. binder. The properties can also be modified by combining (I) with a carrier material consisting of (non)woven (in)organic fabric, rubber or rubber elastomers or other known solid of foamed prods. USE/ADVANTAGE - Used e.g. for the prodn. of highly elastic joint sealing tapes, etc. which undergo reversible swelling on contact with water. (I) provide a better permanent seal under wet conditions than prior-art systems (e.g. elastomer sections, metal plates embedded in concrete) and are suitable for use in constructional joints, sewage pipes, etc. esp. where elasticity is also required

Description

It is known to use so-called hydrogels by reaction between certain isocyanate prepolymers and produce water. Isocyanate prepolymers are preferred for these reactions Products used by the reaction of linear polyethers with terminal OH groups with Di isocyanates, preferably with toluene diisocyanate (TDI), but also with other known diiso cyanates such as MDI, HDI or IPDI are produced with an excess of the diisocyanate used.

The preparation of such products obtained by addition reaction is familiar to the person skilled in the art and therefore need not be described in more detail. A summary with extensive cross-references to the relevant literature is in the relevant standard work:
Vieweg / Höchtlen / Oertel: "Kunststoff-Handbuch, Vol. 7 Polyurethane", 1983, published by Carl Hanser, Munich.
to find.

Other products with a similar structure familiar to those skilled in the art are those resulting from the reaction between diisocyanates and water using amines / diamines / polyamines or OH functional compounds obtained polyurea gels with massive or microporous structure, such as they in numerous writings, e.g. B. also described in DE 25 21 265, DE 23 47 299 and DE 25 38 716 ben are.

Such known products are e.g. B. as a carrier material for agents dissolved in the water of reaction such as fragrances, as an injection gel for seals by injecting the liquid product into cracks, with hard fillers as grinding media or as dressing materials (cooling by water release) turns.

Such hydrogels containing water naturally shrink through in a non-humid environment Evaporation of the trapped water. As is known, this shrinking process is reversible d. H. A dried hydrogel can also absorb the water once it has been given and thereby swell back to its original volume. A swelling process such as that used in manufacturing Water-swellable sealing tapes according to the claim of this invention is necessary for Hydrogels, however, do not known to swell back to their original volume. A swelling process like it is meant according to the claim of this invention, expressly requires an additional swelling triggered beyond the original initial volume of a body during its manufacture through additional storage of water in the structure of the body while enlarging its Volume.  

The present invention therefore makes use of the experience known to the person skilled in the art that certain substances are able to rapidly absorb large amounts of water with the formation of gel-like structures. These substances include certain clay minerals from the group of montmorrillonites as well as highly polymeric carbohydrates, such as those used for. B. in
Ullmann, Encyclopedia of Technical Chemistry, Vol. 19, Verlag Chemie, Weinheim.
are described, as well as certain, partially crosslinked polymeric amides, ammonium and alkali salts of acrylic acids and the (partially crosslinked) acids themselves.

Such, well-known to the expert water-absorbing acrylates are under the trivial name "super absorber" on an industrial scale, for. B. manufactured as a water-thawing aid for hygiene applications. Detailed information on these products can be found in numerous company publications (Arakawa Chemical, J-Osaka "Arasorb"; BASF AG, D-Ludwigshafen, "Luqua sorb"; Stockhausen GmbH, D-Krefeld, "Favor" and others); Information on the chemistry of these products in:
Rauch-Puntigam / Völker: Acrylic and methacrylic compounds, Springer-Verlag Berlin, Heidelberg, New York, 1967.
It was extremely surprising and not to be expected that such products can be combined with hydrophilic diisocyanate prepolymers as binders and products which result from these products by reaction with known chain extenders such as water, alcohols, polyamines or mixtures of these substances in a smooth reaction highly elastic sealing tapes can be formed and are characterized by an excellent, permanently reversible swelling behavior in contact with water.

As already mentioned, the hydrophilic diisocyanate prepolymers used as binders are everyone Products familiar to those skilled in the art, preferably based on tolylene diisocyanate (TDI) as isocyanate sieren. However, all other two and multifunctional isocyanates or Kombina can ions of these isocyanates can be used to prepare the prepolymers. These are also suitable ten isocyanates are u. a. described in detail in the already cited plastics manual, vol. 7.

The conversion of the isocyanates to the hydrophilic prepolymer takes place with linear or only weakly branched polyethers with reactive hydroxyl groups as the polyol component, preferably with ethoxylated or propoxylated glycols or their mixtures, one used for the preparation such polyethers of this type are preferably used, whose MOL weight is between 400 and 10,000 lies.  

The prepolymers are prepared by the Um processes which are well known to those skilled in the art settlement of the polyols with the diisocyanate in closed reactors, preferably under inert gas, the diisocyanate being used in excess in amounts such that ultimately still liquid reaction products with free, still reactive NCC group.

However, large-scale technology is preferred for the manufacture of the products according to the invention nically manufactured and therefore inexpensive hydrophilic prepolymers of the described Gat tung. Only as examples of suitable prepolymers with the desired properties Products "Hypol 2000 and Hypol 3000", manufacturer GRACE-Rexolin or. "RESIGAST GH 90 and GH 96 ", manufacturer Resina-Chemie; or" Polygrout W1 or W2 ", manufacturer Daiichi Kogyo Seiyaku; ge called. Of course, the documents DE 25 38 718, DE already cited can also be used 23 47 299 and 25 21 265 and further in the plastic handbook also cited already hydrophilic prepolymers for the manufacture of products according to the claim of this invention be used.

Any expert will also be able to find other suitable prepolymers on the market to find the genus described or such by varying the known parameters put.

In the simplest case, the process for the production of water-swellable products is that the selected, hydrophilic swelling agent in ground form (similar to a filler) in the submitted Prepolymer incorporated and this batch then mixed intimately with water and immediately under shape discharge - for example through a corresponding molding nozzle or into a casting mold - zer a tough elastic body with the shaping unit of appropriate geometry is created.

It can also be done in such a way that the hydrophilic swelling agent is initially mixed with an inert liquid substance that is compatible with the prepolymer, but is not reactive, is mixed and then the Prepolymer is incorporated.

The mixtures can, if necessary, inert mineral flours or others to make the recipe cheaper known fillers such. B. wood flour, rubber flour or granules or the like, generally for use as filler known to any expert - contain substances. Also well known to those skilled in the art fabrics such as B. plasticizers, soft resins or resin solutions can be used to achieve certain egg properties are also used, as are pigments for coloring.

Instead of pure water as a reaction component for the prepolymer mixture, certain water-containing emulsions or solutions or dispersions of high polymers in water can also be used. With such additives, both the solids content of the resulting product can be further increased and a certain modification of the desired properties can be achieved. Suitable and preferred in this sense are, for. B. emulsions of bitumen in water, the known dispersions of olefinically unsaturated compounds in water, described for. B. in
Hölscher, dispersions of synthetic high polymers, Springer Verlag, Berlin, 1969 (2 vols.)
or solutions of polyvinyl alcohol in water. It goes without saying that the aqueous reaction component can also contain additional fillers, additives or additives.

The source joint sealing tapes which can be produced according to the claim of the present invention can either made as a completely solid body or with a microporous or more or we niger coarse-cell structure as foam.

To control the reaction between the diisocyanate prepolymer and the reaction partners Chain extenders used can be those from the chemistry of polyurethanes well-known catalysts and additives (see also the previously cited Plastic manual, Vol. VII) can be used. Just be an example of such catalysts tertiary amines such as diazobicyclooctane, dimethylethanolamine, dimethylcyclohexylamine or organic Metal compounds such as dibutyltin dilaurate mentioned, as an example of suitable additives silicone surfactants as foam stabilizers, antioxidants, light stabilizers, emulsifiers and the like, the subject Substances well known as additives and additives for polymers and elastomers.  

Examples

These examples describe the new products according to the claim of this invention. This case games stand only for typical embodiments of the invention according to the present claim.

It is of course possible for any person skilled in the art to simply describe the products described by simple ver Change in the knowledge communicated according to the invention to vary further. The claim from the The present invention is also applied to such modified embodiments of the invention.

example 1

A mixture A is produced from 50 pbw of polyethylene glycol with a MW of 600 and 10 pbw Propylene carbonate. This premix is 30 GT of a Pro known as "Super Absorber" product called Norsolor Aqua-Keep 10 SHB and this mixture as A-1 draws. Mixture A-1 is mixed with 50 pbw of a hydrophilic diisocyanate prepolymer with the Be Drawing Resicast GH-90 mixed, immediately after mixing, volumetrically in a ratio of 1: 1 mixed with water and placed in a rectangular shape. The first liquid product rises to a tough, elastic body within 1 minute, which accurately reproduces the geometry of the shape det and when in contact with water its volume is increased threefold by swelling without losing its rubber-elastic properties.

As expected, the product shrinks by volume when stored in a dry environment of the incorporated water in order to then quickly be three times as fast in water swell existing dimension in the manufacture. This process can be done as often as you like be repeated.

Example 2

A basic mixture B is prepared as described in Example 1. This basic mi A finely ground polyammonium acrylate analogous to mixture A-1 is added to mixture B, which by polymerization of partially neutralized acrylic acid with ammonia (pH approx. 6) with co-use tion of 2% of a multifunctional acrylic monomer as a crosslinker in known technology was put. With this basic approach, a Mi was further described exactly as in Example 1 with Polygrout W-1 and manufactured and proceed as described in Example 1.

The resulting product corresponds in its swelling behavior and its rubber-like properties the product from Example 1.  

Example 3

A basic mixture C is prepared as described in Example 1. This basic mi A finely ground polyacrylamide analogous to mixture A-1 is added to mixture C, which consists of Polymerization of a solution of acrylamide in water using 2% of one polyfunctional acrylic monomers as a crosslinker was produced in known technology. With the This master batch was further described as in Example 1, a mixture with Polygrout W- 1 prepared and proceed as described in Example 1.

The resulting product corresponds in its swelling behavior and its rubber-like properties the product from Example 1.

Example 4

A mixture D is produced from 50 pbw of polypropylene glycol with a MW of 2000 and 10 > Propylene carbonate. This premix is 30 GT of a Pro known as "Super Absorber" product called Norsolor Aqua-Keep 10 SHB and this mixture as D-1 draws. The mixture D-1 is with 50 pbw of a hydrophilic diisocyanate prepolymer with the Be Drawing Hypol 2000 mixed, immediately after mixing, volumetrically in a 1: 1 ratio Mixed water and put in a rectangular shape. The initially liquid product solidified becomes a tough, elastic body with a fine porous foam structure within a few minutes Geometry of the shape reproduces exactly and swells strongly in contact with water without losing its gum to lose mielastic properties.

As expected, the product shrinks when stored in a dry environment and then shrinks into Swell water again. This process can be repeated any number of times.

Example 5

A mixture E is produced from 50 pbw of chlorinated paraffin with the designation "chlorinated paraffin Maximum 59 "and 15 GT propylene carbonate. This premix is 35 GT one as" super absorber "weakly cross-linked sodium acrylates with the name Norsolor Aqua-Keep 10 SHB and 10 GT kaolin incorporated and this mixture referred to as E-1. The mixture E-1 will with 60 pbw of a hydrophilic diisocyanate prepolymer called Resicast GH-90 ver mixes, immediately after mixing, volumetrically in a ratio of 1: 1 with an aqueous polymer dis persion mixed with the name Acronal 290 (FK 50%) and poured into a rectangular shape ben. The initially liquid product solidifies into a tough elastic body within 1 minute, that exactly reproduces the geometry of the shape and swells three times when it comes into contact with water, oh ne losing its rubber-elastic properties.

As expected, the product shrinks when stored in a dry environment and then shrinks into Rapidly swell water to three times the volume present during manufacture len. This process can be repeated any number of times.  

Swellable seals and sealing profiles to secure joints against the ingress of water are a novel problem solution in construction technology. They are increasingly replacing conventional ones Process of securing joints using elastomer profiles or concreted metal sheets with clear tech niche advantages.

Similar applications for swellable seals are sealing profiles for sewage pipes and Sewer pipes. In these applications too, active, swellable starting materials can be used provided seals ensure the necessary tightness much better over long periods of time, than is possible with conventional seals.

On structures, technically unavoidable joints and penetrations, z. B. protected against the ingress of water by pipes. These joints are either as so-called construction joints due to technical reasons or are planned constructively to prevent cracks in Building structures - causes z. B. by the natural shrinkage of the concrete at its hardening tion - or to avoid the temperature-related changes in length of the building. At Baukon Structures from prefabricated parts inevitably result in joints at the joints of these prefabricated parts parts.

According to the prior art so-called for the necessary sealing of such joints Swelling joint sealing tapes are used. These are products that are geo metrically designed profiles can be available and which are installed in the joint space. These profiles swell on contact with water. Through the associated with the swelling process Volume increase and the resulting contact pressure (swelling pressure) should this Ouellfu Seal the existing joint space against the penetrating water.

These, according to the prior art, joint tapes are made of water-swellable substances systemic with considerable disadvantages.

Thus, expansion joint tapes are known, which are preferably made from highly swellable clay minerals from the Genus of Montmorrillonite (preferably bentonites) exist with suitable binders are either fixed on carriers or in a matrix of a binder z. B. not vulcanized butyl rubber or bitumen - similar to a putty - are included. disadvantage of these known swellable sealing tapes is that use the product that triggers swelling The bentonite cannot be fixed sufficiently firmly on or in the carrier and the swelling joint tape upon contact with a lot of water it loses its strength and is finally dissolved.

DE-OS 39 12 765 describes a swelling joint tape, which is characterized by polymerization reactions act olefinically unsaturated monomers with swellable fillers and, if necessary, as blending agents the polymer dispersions or bitumen emulsions by direct polymerization of the monomers in is produced in situ. The production of a swelling joint tape using this technique is extraordinary complex and not unproblematic because of the difficult to control, as is known to the expert Polymerization reaction. However, an exact reaction procedure is always the same for a qualitatively equivalent one Product absolutely necessary, how easy to see.  

In addition, expansion joint tapes that are produced according to this prior art are relatively hard te, little elastic body, for this reason alone for many applications in construction practice are not suitable. As an example of such applications for which this well-known joint seal tape is not suitable, are called swellable expansion joint tapes, which are specified in the design ne movement joints can be installed.

DE-OS 27 37 774 describes a swellable joint material, which by installing a reaction product from maleic anhydride in a synthetic rubber by joint vulcanization is provided. The disadvantage of this known product is that the swellability, ie the essential egg property of a swelling joint sealing tape, is not very pronounced. Like practical experience show, such known expansion joint tapes are also subject to rapid aging, i. H. to multiple changes between swollen and shrunk to the original volume Volume, the source volume originally reached goes up to values of approx. 40% of the initial value te back. After all, even products according to this state of the art are not sufficiently gum Mielastic to be used as sealing tapes for expansion joints.

The object of the present invention was therefore to produce a sealant which swells in water to deliver, which avoids the known disadvantages of sealing materials which swell in water due to high elasticity, uniform and strong swelling behavior even with frequent cycle changes between wet and dry and simple production from casting technology available and thus price value, distinguish raw materials.

This object is according to the invention in a surprisingly simple and elegant way solve!

Claims (12)

1. Water-swellable sealing material with rubber-like properties, characterized in that it consists of a matrix which is prepared by reaction of known hydrophilic isocyanate prepolymers with chain extenders such as water, alcohols or amines and the known, strong in water swellable substances are incorporated as a source component. The ratio of isocyanate prepolymer to chain extender can be 1 to 9 to 9 to 1. 2. Water-swellable sealing material with rubber-like properties according to claim 1, because characterized in that it is in homogeneously massive, microporous or cellular foam-like Structure can exist. 3. Water-swellable sealing material with rubber-like properties according to claim 1 and 2, characterized in that it is in addition to the modification of the properties and the mine tion of shrinkage by drying known dispersions of high polymer plastics in May contain water or solutions of water-soluble high polymer in water. The ratio of isocyanate prepolymer these additives can be 1 to 9 to 9 to 1. 4. Water-swellable sealing material with rubber-like properties according to claim 1 to 3, characterized in that it is in addition to the modification of the properties and the mine tion of shrinkage by drying known bitumen, asphalt or emulsions Tar in water or by combining such emulsions with those mentioned in claim 3 Dispersions of high polymer plastics in water can contain modified emulsions. The The ratio of isocyanate prepolymer to these additives can be 1 to 9 to 9 to 1. 5. Water-swellable sealing material with rubber-like properties according to claim 1, 2 and 4, characterized in that in addition to the modification of the properties and the min change in shrinkage by drying, known as a solid and defi nized grain size, ground inorganic or organic fillers or fibrous materials and color May contain pigments. The proportion of these additives in the overall formulation can be 1 to 150%, based on the binder be.   6. Water-swellable sealing material with rubber-like properties according to claim 1, 2, 3 and 5, characterized in that it is in addition to the modification of the properties on a carrier material applied and connected to this or such a material in the sealing material is incorporated. The carrier material can be made from fabrics or nonwovens known per se exist, which are made of inorganic or inorganic raw materials. 7. Water-swellable sealing material with rubber-like properties according to claim 1, 2, 3 and 6, characterized in that in addition to the modification of the properties to a carrier germ material applied and connected to this or such a material in the sealing material is incorporated. The carrier material can be made of materials known per se, such as rubber or rubber-like elastomers or other solid or foamed materials known per se Products. 8. Water-swellable sealing material with rubber-like properties according to claims 1 to 7, characterized in that it is the substance causing the desired swelling itself the trivial name "Super Absorber" contains known products. These super absorbers can polymeric salts or amides of acrylic acids. The proportion of these super absorbers can be 1 to 80% based on the binder, preferably 5 to 65%, based on the binder, especially before be 10 to 50%, based on the binder and preferably depends on the expected Source volume of the products. 9. Water-swellable sealing material with rubber-like properties according to claims 1 to 8, characterized in that it is finely ground as the substance causing the desired swelling contains inorganic substances, such as the bentonites belonging to the Mantmorrillonite family. The amount this bentonite can be 1 to 200%, based on the binder, preferably 5 to 100%, based on the binder, particularly preferably 10 to 75%, based on the binder. 10. Water-swellable sealing material with rubber-like properties according to claims 1 to 9, characterized in that it corresponds to any geometric shape by extrusion accordingly shaped nozzles can be produced. 11. Water-swellable sealing material with rubber-like properties according to claims 1 to 8, characterized in that it is produced as a semi-finished product in the form of foils and tapes can. The actual seals can be made from this semi-finished product by mechanical processing e.g. B. cutting, punching or similar, known methods.   12. Water-swellable sealing material with rubber-like properties according to claims 1 to 8, characterized in that it is a finished product with any geometry by known spray casting process, e.g. B. in reaction injection molding machines (two- or multi-component injection molding machine nen) can be produced.