Vinyl-terminated prepolymers having low viscosity and good water solubility

Abstract

A polyether having a functional group that is reactive to isocyanate with at least one polyisocyanate, which has an average isocyanate functionality in the range of 2.4 to 3.5, and at least one vinyl compound, which has a functional group that is reactive to isocyanate, wherein the molar ratio of polyether to vinyl compound lies in the range of 3:1 to 1:3 and the ratio of the sum of the molar quantities of polyether and vinyl compounds to isocyanate groups lies in the range of 1.5:1 to U.5. Corresponding vinylterminated prepolymers have the advantage of low visocity together with good water solubility and therefore can be used advantageously for applications as injection agents.

Claims

1. A method for sealing of built structures, tunnels or mines with an injection medium, comprising: providing an injection medium comprising a vinyl-terminated prepolymer by reaction of i) a polyether having a functional group reactive toward isocyanates with ii) at least one polyisocyanate having a mean isocyanate functionality in the range from 2.4 to 3.5, and iii) at least one vinyl compound having a functional group reactive toward isocyanates, wherein the molar ratio of polyether i) to vinyl compound iii) is in the range from 3:1 to 1:3 and the ratio of the sum total of the molar amounts of polyether and vinyl compound to isocyanate groups ii) is in the range from 1.5:1 to 1:1.5, wherein the polyether has exactly one functional group reactive with NCO group or the vinyl compound has exactly one functional group reactive with NCO group, wherein the proportion of the polyether in the vinyl-terminated prepolymer obtained via the reaction amounts to at least 30% by weight, based on the total weight of the prepolymer, and wherein the vinyl-terminated prepolymer is injected into a cavity together with a free-radical initiator and optionally further components; and polymerizing said injection medium.

2. The method as claimed in claim 1, wherein the prepolymer contains less than 10% by weight of reaction products formed from polyoxyalkylenepolyols based on starter molecules having three or more hydroxyl functionalities, in which all or some of the hydroxyl functionalities have been reacted with methacrylic acid.

3. The method as claimed in claim 1, wherein the polyether having a functional group reactive toward isocyanates is a linear polyethylene glycol, polypropylene glycol or a mixed polyethylene glycol/polypropylene glycol copolymer or block copolymer.

4. The method as claimed in claim 1, wherein the polyether having a functional group reactive toward isocyanates has a molecular weight Mw in the range from 200 to 5000.

5. The method as claimed in claim 1, wherein the at least one vinyl compound is selected from alcohols, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, and amines.

6. The method as claimed in claim 1, wherein the at least one polyisocyanate comprises a triisocyanate.

7. The method as claimed in claim 6, wherein the at least one polyisocyanate additionally comprises an aliphatic diisocyanate.

8. The method as claimed in claim 1, wherein the reaction additionally includes iv) an aromatic or aliphatic compound which cannot be qualified either as a polyether i) or as a vinyl compound iii), having a functional group reactive toward isocyanates.

9. A process for producing an injection medium, comprising preparing a vinyl-terminated polymer by a method comprising: i) the addition of at least one polyisocyanate having a mean isocyanate functionality in the range from 2.4 to 3.5 either to a polyether constituent having a functional group reactive toward isocyanates or to at least one vinyl compound constituent having a functional group reactive toward isocyanates, ii) allowing the isocyanate groups to react with the functional groups reactive toward isocyanates, iii) depending on the constituent initially charged in step i), the addition of the other constituent to the reaction product formed from polyisocyanate and the initially charged constituent, and iv) allowing the reaction product formed from polyisocyanate and the initially charged constituent to react with the other constituent, wherein the other constituent is the at least one vinyl compound constituent having a functional group reactive toward isocyanates when the constituent initially charged in step i) is the polyether constituent having a functional group reactive toward isocyanates, and vice versa, and the addition of a free-radical initiator and optionally further components, wherein the molar ratio of polyether to vinyl compound is in the range from 3:1 to 1:3 and the ratio of the sum total of the molar amounts of polyether and vinyl compound to isocyanate groups ii) is in the range from 1.5:1 to 1:1.5, wherein the polyether has exactly one functional group reactive with NCO group or the vinyl compound has exactly one functional group reactive with NCO group, wherein the proportion of the polyether in the vinyl-terminated prepolymer obtained via the reaction amounts to at least 30% by weight, based on the total weight of the polymer.

10. A process for producing an injection medium, comprising the preparation of a vinyl-terminated prepolymer by a method comprising: i) the addition of at least one polyisocyanate having a mean isocyanate functionality in the range from 2.4 to 3.5 to a mixture of a polyether having a functional group reactive toward isocyanates and at least one vinyl compound having a functional group reactive toward isocyanates, ii) allowing the polyisocyanate to react with the polyether and the vinyl compound, wherein the molar ratio of polyether to vinyl compound is in the range from 3:1 to 1:3 and the ratio of the sum total of the molar amounts of polyether and vinyl compound to isocyanate groups ii) is in the range from 1.5:1 to 1:1.5, wherein the polyether has exactly one functional group reactive with NCO group or the vinyl compound has exactly one functional group reactive with NCO group, wherein the proportion of the polyether in the vinyl-terminated prepolymer obtained via the reaction amounts to at least 30% by weight, based on the total weight of the polymer.

11. The process as claimed in claim 9, wherein, for the reaction of the isocyanate groups with the functional groups reactive toward isocyanates, a catalyst is added.

12. The method as claimed in claim 1, wherein the proportion of the polyether in the vinyl-terminated prepolymer amounts to at least 33% by weight, based on the total weight of the prepolymer.

13. The method as claimed in claim 2, wherein the prepolymer contains less than 5% by weight of reaction products formed from polyoxyalkylenepolyols based on starter molecules having three or more hydroxyl functionalities, in which all or some of the hydroxyl functionalities have been reacted with methacrylic acid.

14. The method as claimed in claim 3, wherein the polyether having a functional group reactive toward isocyanates is a polyethylene glycol modified at one end with an alkoxy group, preferably a methoxy group.

15. The method as claimed in claim 4, wherein the polyether having a functional group reactive toward isocyanates has a molecular weight Mw in the range from 300 to 2000.

16. The method as claimed in claim 5, wherein the at least one vinyl compound is selected from an allyl alcohol and 2-(tert-butylamino)ethyl methacrylate.

17. The method as claimed in claim 6, wherein the at least one polyisocyanate comprises an aliphatic triisocyanate.

18. The method as claimed in claim 6, wherein the at least one polyisocyanate comprises a trimer of hexamethylene diisocyanate.

19. The method as claimed in claim 7, wherein the at least one polyisocyanate additionally comprises an isophorone diisocyanate.

20. The method as claimed in claim 1, wherein the polyether has exactly one functional group reactive with NCO group and the vinyl compound has exactly one functional group reactive with NCO group.

Description

EXAMPLES

(1) Determination of the Relevant Properties

(2) The viscosities of the prepolymers and of the 50% aqueous solutions of the prepolymers were determined at 23 C. with a Physica MCR101 viscometer according to ISO 3219 with a coaxial cylinder measurement system (at a cone angle of 120).

(3) The appearance of the 50% aqueous solution was determined by inspection. The observation clear indicates that the polymer had dissolved.

(4) The gel time was determined for a 50% aqueous solution of the prepolymers (25 g) with addition of 0.5 g of a 10% solution of sodium persulfate in water and 0.25 g of triethanolamine. The gel time corresponds to the time before which the first gel structures are visually apparent in the reaction solution.

(5) Materials Used:

(6) TABLE-US-00001 Aduxol VP-6685 polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 2258 and an ethylene oxide content of 41%; the ethylene oxide forms the end blocks (Schrer & Schlpfer AG) Aduxol VP-11115 polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 1700 and an ethylene oxide content of 50%; the ethylene oxide forms the middle block (Schrer & Schlpfer AG) Aduxol VP-11122 mono-methoxy-terminated polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 500 and an ethylene oxide content of 50%; the polyethylene oxide is methoxy- modified (Schrer & Schlpfer AG) Aduxol VP-11121 mono-methoxy-terminated polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 1000 and an ethylene oxide content of 50%; the polyethylene oxide is methoxy-modified (Schrer & Schlpfer AG) Aduxol VP-11132 mono-methoxy-terminated polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 500 and an ethylene oxide content of 50%; the polypropylene oxide is methoxy-modified (Schrer & Schlpfer AG) Aduxol VP-11128 mono-methoxy-terminated polyethylene oxide/polypropylene oxide block copolymer with a molecular weight Mw of 1000 and an ethylene oxide content of 50%; the polypropylene oxide is methoxy-modified (Schrer & Schlpfer AG) MPEG500 mono-methoxy-terminated polyethylene glycol with a molecular weight Mw of 500 (BASF) Desmodur T80P mixture of tolylene 2,4- and 2,6- diisocyanate in a ratio of 80:20 (Bayer) Vestanat IPDI isophorone diisocyanate (Evonik) Desmodur N3300 hexamethylene diisocyanate trimer (Bayer) 2-tBAEMA 2-(tert-butylamino)ethyl methacrylate (BASF) DBTL dibutyltin dilaurate, catalyst (Azelis) OH-TEMPO 4-hydroxy-2,2,6,6-tetramethylpiperidin- 1-oxyl, free-radical scavenger (Evonik)
Preliminary Experiments

(7) In preliminary experiments, first of all, prepolymers based on isocyanates and polyether diols were prepared (V-1 to V-3). For this purpose, the polyether diols were reacted in a first stage with diisocyanates to give an intermediate. In a second stage, hydroxyethyl methacrylate (HEMA) was then added, in order to modify the isocyanate groups still present with vinyl functionalities.

(8) In experiments V-1 and V-3, however, the system was already found to be completely polymerized after the first stage. When an aliphatic isocyanate (V-2) was used in place of an aromatic diisocyanate, a product that had a viscosity of about 50 000 mPas was obtained after the second stage.

(9) In a second set of experiments, a trifunctional isocyanate (Desmodur N3300) was reacted first with hydroxyethyl methacrylate and, in V-4, additionally with MPEG 500. The intermediate obtained was reacted in a second step with a dihydroxy-functional polyether (Aduxol VP-6685) to give the end product. In experiments V-4 to V-6, however, a very high viscosity of about 100 000 mPas or more was found for the products obtained, which indicates a significant proportion of chain extension.

(10) The results of these preliminary studies and the compositions of the products are shown in table 1 below.

(11) TABLE-US-00002 TABLE 1 V-1 V-2 V-3 V-4 V-5 V-6 1st stage Aduxol VP-6685 100 100 Aduxol VP-11115 100 MPEG 500 62 Desmodur T8OP 17.5 22.5 Vestanat IPDI 22.1 Desmodur N3300 59.4 57.8 122 HEMA 9.8 13 55 Ethanol 4.6 DBTL 0.005 0.01 0.01 0.01 OH-Tempo 0.02 0.02 0.02 2nd stage DBTL 0.005 OH-TEMPO 0.02 0.02 0.02 HEMA 13 12.9 16.7 Aduxol VP-6685 94 94 185 Properties Viscosity of the reaction mixture 50000 reaction mixture 99000 250000 340000 prepolymer [mPa .Math. s] polymerizes in polymerizes in 1st stage 1st stage Appearance of the 50% clear clear clear clear aqueous solution Viscosity as a 50% 1200 3740 38000 15000 aqueous solution [mPa .Math. s] Gel time [min] 40 29 12 7

Example 1

(12) Inventive compositions 1 to 8 were prepared by reacting, in a one-pot reaction (compositions 1 to 7) or in a two-stage reaction, various polyethers functionalized with methoxy groups at one end and having a hydroxyl function with a trifunctional isocyanate (Desmodur N3300) and a hydroxy-functional acrylate (hydroxyethyl methacrylate or hydroxypropyl methacrylate (HPMA); compositions 1 to 7) or an amine-functional acrylate ((2-(tert-butylamino)ethyl methacrylate; composition 8). All products exhibited viscosities in the range from about 10 000 to 50 000 mPa.Math.s and had good processibility. The gel time of the compositions obtained was in the range from 7 to 30 min. The exact compositions and the particular properties thereof are shown in table 2.

(13) TABLE-US-00003 TABLE 2 1 2 3 4 5 6 7 8 1st stage Aduxol VP-11122 75 Aduxol VP-11121 143 Aduxol VP-11132 75 Aduxol VP-11128 143 MPEG500 60 75 75 75 Desmodur N3300 61 61 61 61 61 61 61 61 HEMA 20.6 20.6 20.6 20.6 24.7 20.6 HPMA 22.8 DBTL 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 OH-Tempo 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 2nd stage 2-tBAEMA 29.3 Properties Viscosity of the 18000 25000 50000 40000 23000 9250 9550 13600 prepolymer [mPa .Math. s] Appearance of the 50% clear clear clear clear clear clear clear clear aqueous solution Viscosity as a 50% 4980 13500 2035 1720 9100 2175 2450 6700 aqueous solution [mPa .Math. s] Gel time 7 10 11 30 30 24 22 10

Example 2

(14) In further studies, the effect of an addition of difunctional isocyanates on the prepolymers obtained was to be examined. The reference example used for these studies was composition 5 containing trifunctional isocyanate only. In compositions 9, 10 and 11, the mean NCO functionality was reduced to 2.75 or 2.5. In comparative composition 7, the mean NCO functionality was reduced further to 2.24. However, this composition was found to polymerize completely, and so the product obtained had no further utility. Compositions 9 to 11 were still liquid even after storage at room temperature for 2 months, while the prepolymer according to composition 5 solidified after only 2 weeks. In addition, it was not possible to observe any air (in the form of bubbles) in the solution in the case of the 50% solutions of compositions 9 to 11, which was the case for reference composition 5.

(15) The exact compositions of the samples studied and the particular properties thereof are shown in table 3 below.

(16) In a further series of experiments, the effect of different ratios of MPEG 500 and HEMA on the polymer formed was examined. Example 6 was used as a reference for these studies, in which the ratio of MPEG 500 to HEMA was 1:1. In examples 12 and 13, this ratio was adjusted to 1:2 and 2:1 respectively. It was found here that the change in the ratio had only a slight effect on the properties of the prepolymer formed. In all cases, products of good processibility were obtained.

(17) TABLE-US-00004 TABLE 3 5 9 10 11 V-7 6 12 13 1st stage MPEG500 60 60 60 50 60 75 100 100 Desmodur N3300 61 45.8 30.5 45.8 15.3 61 122 61 IPDI 8.8 17.6 8.8 26.4 HEMA 24.7 24.7 24.7 27.5 24.7 20.6 55 13.7 DBTL 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 OH-Tempo 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 NCO functionality 3 2.75 2.5 2.75 2.24 3 3 3 Properties Viscosity of the 23000 18000 14000 14000 polymerizes 9250 31000 7600 prepolymer [mPa .Math. s] Appearance of the 50% clear clear milky opaque clear clear clear aqueous solution Viscosity as a 50% 9100 1400 1000 1350 2175 n.d. 3450 aqueous solution [mPa .Math. s] Gel time [min] 30 20 25 12 24 15 22 n.d. = not determined.

Example 3

(18) In the context of this example, the extent to which the preparation of the vinyl-terminated prepolymers within a sequential or one-pot process affects the resultant properties of the prepolymers was to be examined. For this purpose, in composition 14, MPEG 500 was first reacted with a trifunctional isocyanate (Desmodur N3300) and the product obtained was reacted with hydroxyethyl methacrylate in a second stage to give the end product. In composition 15, the trifunctional isocyanate was first reacted with hydroxyethyl methacrylate and the product obtained was then reacted with MPEG 500 to give the end product. In composition 12, all the components were reacted with one another in a one-pot process. It was found here that the exact process procedure had only a minor effect on the viscosity of the prepolymer obtained (see table 4). Since the one-pot process is associated with the lowest time demands, this process is preferred for the production of the vinyl-terminated prepolymers of the invention.

(19) TABLE-US-00005 TABLE 4 12 14 15 1st stage MPEG500 100 100 Desmodur N3300 122 122 122 HEMA 55 55 DBTL 0.01 0.01 0.01 OH-Tempo 0.02 0.02 0.02 2nd stage HEMA 55 MPEG500 100 Properties Viscosity of the 31000 30000 14000 prepolymer [mPa .Math. s]