DE3843221C1 - Process for the preparation of a liquid polyurethane prepolymer, and the conversion thereof into an open-pore polymer concrete - Google Patents

Abstract

A liquid polyurethane prepolymer is prepared by reacting a polyol mixture comprising from 70 to 95 parts by weight of a linear epsilon -polycaprolactone having a molecular weight of between 500 and 1000 and from 5 to 30 parts by weight of a linear polyethylene glycol having a molecular weight of between 300 and 3000 with from 1.8 to 1.95 equivalents of tolylene diisocyanate, and diluting the product with from 0.3 to 0.7 equivalent, based on the polyol mixture, of a liquid, crude diphenylmethane diisocyanate. The product can be mixed with a mineral mixture and left to set in the presence of moisture to give an open-pore polymer concrete.

Description

Reactive resin concretes are materials in which ver improvement of processing and / or usage properties the hydraulic binder through concrete additives on the Base of synthetic resins, especially reactive resins, replaced is.

An important factor in the assessment and creation of Road surfaces represent their ability to reduce noise of driving, driving and rolling noises. Appropriate a road surface appears that consists of an open-pore, bound pile is formed. This creates the further one Advantage that due to the open pores the water absorption ability and thus drainage effect of the covering very high is.  

As a road surface in road construction is therefore in itself known reaction resin concrete is conceivable. This hardens quickly out, does not crawl under heat and load, is very firm, frost and heat resistant and can be colored reflective. Unsaturated are used as binders for the minerals Polyester resins, epoxy resins, methyl methacrylate resins and Known polyurethane products. So far, however, they are only Applications for the manufacture of machine frames in Considered (Austrian plastics period p. 15 (1984) 1/2, pp. 9-10). Use in the street construction is not described.

The use of a one-component reaction resin as Binder for mineral aggregates is used in the DE-AS 24 51 393 described. It describes a procedure for Production of a bonded with polyurethane / polyurea Reaction resin concrete shown, in which the inorganic Filler is mixed with a polyurethane prepolymer. Before mixing, the filler is moistened with water. After mixing, foaming and setting take place let the mixture within its setting time are processed got to. However, if you use the binder described Production of an open-pored pile, so this has one extremely low strength result, which always leads out breaking individual filler grains. One use this reaction resin is for open-pore road surfaces therefore excluded.  

A process for making a polyurethane prepolymer Connection with terminal isocyanate groups and lower Volatility is in JP-5 31 33 298, referenced in CPI profiles Booklet 1979, Unit 00981 B / 01, and in Chem. Abstracts, Vol. 90, 1979, Section 104 852d. There will be a Polyol - exemplified is polypropylene glycol - with 1.8 to 1.95 equivalent of tolylene diisocyanate and then with Diphenylmethane diisocyanate mixed. Generally the Applicability of the mixture for u. a. Civil engineering and construction specified. As a binder for mineral fillers also this poly based on a single polyol ether polyurethane prepolymer with diphenylmethane diisocya nat content unsuitable if higher strength values should be achieved as they are in road construction because of there occurring high loads are required: accordingly manufactured test specimens show bending and compressive strengths, which are only about a third of the required values; the So the mineral fillers are bound to each other insufficient.

It is further observed that according to the Japanese printing mentioned written prepolymers when reacting with Although water hardens quickly in the surface areas, a skin so formed, however, prevents this Hardening completely and equally in the inner areas done quickly. The consequences are unevenly bound Materials, which is also detrimental to the final strength.  

Based on the latter prior art, the present invention for the object, a method for Her state the position of a liquid polyurethane prepolymer, which hardens quickly and, above all, evenly with water and which in admixture with mineral fillers is such a good binder that reactive resin concrete with significantly higher load capacities than previously manufactured can be, as they are required in road construction. The prepolymer should be so stable that it without Loss of quality long before its use trans can be ported and stored.  

This problem is solved by the in claim 1 Drew process for the production of a liquid poly urethane prepolymers and those specified in the use claim given advantageous further processing to open-pore Reaction resin stress.

In particular, the fact that a polyurethane prepolymer based on a mixture of two polyols is produced with a proportion of 5 to 30 wt .-% poly ethylene glycol (molecular weight of 300 to 3000), together with 70 to 95 wt .-% of a linear ε- Polycaprolactone with a molecular weight between 500 and 1000, stirring only for 30 to 40 minutes and then adding 0.3 to 0.7 equivalent of crude diphenylmethane diisocyanate, leads to a binder which cures particularly uniformly and thereby, in Mixing with mineral fillers, several times higher strength data than is the case with previous reactive resin concrete.

It is immaterial for the invention that the usually put tolylene diisocyanate commercially as a mixture of 2,4- and 2,6-isomers are available; because the relationship these mixtures are complete for the present invention not critical.  

The from z. B. the DE-AS 24 51 393 known, commercially available liche raw diphenylmethane diisocyanate is a Mixture of different diphenylmethane diisocyanate isomers (with a share of the 4,4'-isomers from 30 to 90%) and Trifunctional poly with methylene bridges phenyl isocyanates.

The rapid and even curing of the prepolymer Adding raw diphenylmethane diisocyanate and water is the addition of the linear polyethylene glycol. This serves the Hydrophilization of the mixture to the reactant water too to let it penetrate inside without the outside Areas of impenetrable hydrophobic skin form. Polyethylene glycol as an excess polyol component is, however, in the polyurethane chemistry as strength reducing known; it could not have been foreseen that she would already invent it in accordance with the low proportions of this glycol (deficit), the not cause any significant loss of strength yet contribute to such a high degree of hydrophilicity of the prepolymer, that the setting time is only a third of that known Polyurethane prepolymer would be completely the same moderate curing behavior of the prepolymer also in Inside. In the examples, this fact is with numbers values documented.

The liquid, dilute prepolymer obtained is advantageous adheres in an amount of 3 to 10 parts by weight per 100 Parts by weight of fillers used to create an open pore To produce reaction resin concrete.  

The usual additives are suitable as fillers, such as grit, gravel or sand, rubber granules or building rubble. The grain size can be up to depending on the application 64 mm can be selected and is therefore in conventional loading rich. Mixtures have proven to be particularly advantageous Gravel or grit, sand and rock flour proved to be these substances are characterized in the technical an line TL Min-StB 83.

The sieve line of the mixture is based on the expert common tables for concrete production, e.g. B. the DIN 1045 or DIN 4226, constructed so that an open porous pile is created. This can cause hardening reaction gas escaping without the mixture to find. This open porosity causes fiction very high water absorption according to bound road surfaces and acoustic damping of traffic noise up to 10 dB in the frequency range 1 to 10 kHz.  

The prepolymer produced according to the invention is in air dense packaging is stable for several months. Can him without changing the recipe which was used in the reaction resin concrete known industrial additives, such as catalysts, surface active substances, flame retardants as well Dyes to be added.

Because of the unusually long processability, two different working techniques for making a re Action resin concrete possible: In the first case, dry Minerals pre-mixed with the prepolymer and put in place of use. When taking measures against the Access to air humidity (foil bags or airtight ver closed barrels) the concrete mix is stored indefinitely stable. Otherwise, the minerals and that Resin mixed on site in a conventional concrete mixer and can be installed directly.

Because of the stoichiometry of the prepolymer, the lack of Solvents and because of the possibility of cold processing processing remains the generation of harmful vapors or Odors low. The work can therefore be done by untrained Personnel are made in standard equipment.

The curing of the mixture of prepolymer and fillers happens in a known manner either through the air humidity alone or by spraying with water. For acceleration The sprayed water can be used in the hardening reaction accelerators included, e.g. B. tertiary amines or carbonates the alkali or alkaline earth metals.  

Although the present invention particularly emphasizes reactive resin concretes in road construction, it goes without saying that the use of units with the reactive resin for the production of moldings, such as plates or cylinders, in particular in mechanical engineering, is also possible without disadvantages. No pressure-stable molds are required in the production of such molded parts, since the CO ₂ formed during the hardening reaction can escape due to the open-pore structure of the pile.

Because of the good adhesion of the bandage according to the invention is also the production of composites from Re action resin concrete and other materials, e.g. B. gypsum, kon conventionally bound concrete, asphalt or plastic, possible.

The following examples are intended to illustrate the invention purify. All parts are parts by weight.

example 1

900 parts by weight of ε- polycaprolactone with a molecular weight of 540 and 100 parts of polyethylene glycol with a molecular weight of 600 are mixed with 592 parts by weight of tolylene diisocyanate at room temperature and stirred for 30 minutes. The result is a yellow prepolymer with a viscosity of 100,000 mPa · s and 8.2% NCO content. Then 242 parts by weight of liquid crude diphenylmethane diisocyanate are added and the mixture is stirred for a further 10 minutes. A brown, almost odorless prepolymer is obtained, the viscosity of which is 24,000 mPa · s and which has an NCO content of 11%.

50 parts by weight of this prepolymer become one Given mineral mixture, consisting of 850 parts by weight Grit 2/5, 100 parts by weight of natural sand 0/2 and 50 Ge most of the limestone flour, and in a compulsory mixer Stirred for 5 minutes. The resulting dough-like mixture is with exclusion of moisture in sealed foil bags or airtight barrels can be stored indefinitely.

The mixture is made from the container for on-site processing or the mixing machine on a conventional base poured from gravel in a layer thickness of 2 cm. The curing is complete after 24 hours, that the surface is drivable.

Example 2

In one variant, the curing time is without disadvantages reduced to 5 hours by spraying the surface with Water which contains the amine accelerator 1,4-diaza-bicyclo- [2.2.2.] - Octane contains.  

Example 3

930 parts by weight of ε- polycaprolactone (molecular weight 1000) and 70 parts by weight of polyethylene glycol (molecular weight 800) are mixed with 329 parts by weight of tolylene diisocyanate as in Example 1. 134 parts of liquid crude diphenylmethane diisocyanate are added to the resulting pale yellow, waxy prepolymer (NCO content 5.5%) and the mixture is stirred for a further 10 minutes. This gives a brown, almost odorless prepolymer with a viscosity of 50 Pa · s and an NCO content of 7.7%, which can be processed as in Example 1 or 2.

The reaction resin concrete prepared according to Example 1 was checked for its strength. According to the in Concrete test method according to DIN 1164/7:

The mixture is in a mold with dimensions Cast 160 × 40 × 40 mm and by means of a stamp somewhat condensed. The molded part is used for curing Water sprayed and stored at room temperature for 24 hours.

The following skill values resulted:

• Flexural strength (N / mm ² ): 4.8
• Flexural modulus (N / mm ² ): 450
• Compressive strength (N / mm ² ): 6.5
• Compression at break (%): 5.7

For the formulation of Example 3, poly- ε- poly caprolactone with a significantly higher molecular weight was selected. The test specimens produced as in Example 1 showed significantly lower strengths; here a limit of the usable molecular weight has apparently been reached:

• Flexural strength (N / mm ² ): 2.5
• Flexural modulus (N / mm ² ): 280
• Compressive strength (N / mm ² ): 2.4
• Compression at break (%): 4.1

Example 4

The test specimens were made using a prepolymer prepared from the same starting materials as in Example 1 existed, but in the following proportions:

• 700 parts by weight of ε- polycaprolactone
• 300 parts by weight of polyethylene glycol
• 576 parts by weight of tolylene diisocyanate
• 242 parts by weight of crude diphenylmethane diisocyanate

High-strength, open-pore reaction resin concretes were created:

• Flexural strength (N / mm ² ): 3.7
• Flexural modulus (N / mm ² ): 320
• Compressive strength (N / mm ² ): 4.2
• Compression at break (%): 3.4

Test specimens according to Examples 1 and 4, but each in the Variant of Example 2 were produced, did not result from the strengths noted above divergent values. All of these strengths point to that Presence of particularly suitable for road surfaces open-pore reaction resin concrete close what through Construction and testing of test tracks in the laboratory as well as in the Site was confirmed. There was no crumbling from Heap particles instead; the requirements mentioned at the beginning on road surfaces were met.

In contrast to the examples mentioned, fails Use of a reaction resin according to DE-AS 24 51 393 in an open-pored pile already the production of a Test specimen that this after curing at Demolding always breaks.

However, if you use the piles that are required in this publication, namely with cavities that can be largely filled with reactive resin of any kind, the corresponding test specimens (and thus also a road surface) always have an inadequate compressive strength after foaming and setting less than 1 N / mm ² .

Claims (2)

1. A process for the preparation of a liquid polyurethane prepolymer by reacting a polyol with 1.8 to 1.95 equivalent of tolylene diisocyanate to a fully reacted product and mixing this product with liquid diphenylmethane diisocyanate, characterized in that a polyol mixture, be standing as polyol from 70 to 95 parts by weight of a linear ε- polycaprolactone with a molecular weight between 500 and 1000 and from 5 to 30 parts by weight of a linear polyethylene glycol with a molecular weight between 300 and 3000, the reaction components mixed with stirring for 30 to 40 minutes, allowed to react and the product diluted with 0.3 to 0.7 equivalent, based on the polyol mixture, of liquid crude diphenylmethane diisocyanate. 2. Use of the liquid obtained according to claim 1 Polyurethane prepolymers as binders together with inorganic fillers and under the influence of Moisture for an open-pore reactive resin concrete.