Indoline-Nitroxide Radical as Stabiliser and Inhibitor for Reaction Resins, Reaction Resins Containing Same and Use Thereof

Abstract

Use of a stable indole-nitroxide radical as a stabilizer and/or inhibitor for resin mixtures and reactive resin mortars is described on the basis of radically curable compounds. Resin mixtures and reactive resin mortars may be made stable in storage very effectively using the indole nitroxide radical and the pot life of mortar compositions can be adjusted in a targeted manner.

Claims

1. A use of a stable nitroxide radical as a stabilizer and/or inhibitor for a resin mixture or a reactive resin mixture based on radically curable compounds, wherein the stable nitroxide radical is selected from compounds of general formula (I) ##STR00003## wherein A is a hydrocarbon group which form an aromatic, optionally substituted ring with the two carbon atoms to which it is bound, wherein the substituents may constitute one or more optionally substituted aromatic or aliphatic condensed rings; R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be the same or different and each denotes independently of the others a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group, OH, OR.sup.5, COOH, COOR.sup.6 or CN; R.sup.3 and R.sup.4X, where X is O or NR.sup.7 and R.sup.5, R.sup.6, R.sup.7 each represents an alkyl, alkenyl, aryl or aralkyl group.

2. The use according to claim 1, wherein in formula (I) at least one of R.sup.1 and R.sup.2 denotes a group with a molecular weight greater than 15 and/or R.sup.3 and R.sup.4X wherein X is defined as given above and/or R.sup.1 denotes an aryl moiety such as phenyl or mesityl and R.sup.2 denotes a C.sub.1-C.sub.4 alkyl moiety such as methyl, ethyl, isopropyl, n-butyl, an aryl moiety such as phenyl, a benzyl or allyl moiety.

3. The use according to claim 2, wherein the stable nitroxide radical is selected from compounds of general formula (II) ##STR00004## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are defined in claim 1; R.sup.8 to R.sup.11 may be the same or different and each denotes, independently of one another, water or a group as defined for R.sup.1 to R.sup.4; or R.sup.8 and R.sup.9 or R.sup.9 and R.sup.10 or R.sup.10 and R.sup.11 are joined together to form an aliphatic or aromatic cycle.

4. The use according to claim 3, wherein the stable nitroxide radical is 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide.

5. The use according to any one of the preceding claims, wherein the radically curable compound is obtained by reacting di- and/or higher functional isocyanates with suitable acryl compounds, optionally with the participation of hydroxy compounds containing at least two hydroxyl groups each.

6. The use according to any one of the preceding claims, wherein the reactive resin mortar contains at least one inorganic additive, selected from the group consisting of fillers, thickeners, thixotropy agents, nonreactive solvents, agents to improve flowability and/or wetting agents.

7. The use according to claim 6, wherein the at least one inorganic additive is cement and/or quartz sand.

8. A resin mixture comprising at least one radically curable compound, at least one reactive diluent and a stabilizer and/or inhibitor wherein the stabilizer and/or inhibitor is/are a stable nitroxide radical which is selected from compounds of general formula (I) ##STR00005## wherein A is a hydrocarbon group which form an aromatic, optionally substituted ring with the two carbon atoms to which it is bound, wherein the substituents may constitute one or more optionally substituted aromatic or aliphatic condensed rings; R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be the same or different and each denotes independently of the others a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or an aralkyl group, OH, OR.sup.5, COOH, COOR.sup.6 or CN; R.sup.3 and R.sup.4X, where X is O or NR.sup.7 and R.sup.5, R.sup.6, R.sup.7 each represents an alkyl, alkenyl, aryl or aralkyl group.

9. The resin mixture according to claim 8, wherein in formula (I) at least one of R.sup.1 and R.sup.2 denotes a group with the molecular weight greater than 15 and/or R.sup.3 and R.sup.4X where X is defined as given above and/or R.sup.1 denotes an aryl moiety such as phenyl or mesityl and R.sup.2 denotes a C.sub.1-C.sub.4 alkyl moiety such as methyl, ethyl, isopropyl, n-butyl, an aryl moiety such as phenyl, a benzyl moiety or an allyl moiety.

10. The resin mixture according to claim 9, wherein the stable nitroxide radical is selected from compounds of general formula (II) ##STR00006## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are defined in claim 1; R.sup.8 to R.sup.11 may be the same or different and each denotes, independently of one another, water or a group as defined for R.sup.1 to R.sup.4; or R.sup.8 and R.sup.9 or R.sup.9 and R.sup.10 or R.sup.10 and R.sup.11 are joined together to form an aliphatic or aromatic cycle.

11. The resin mixture according to any one of claims 8 to 10, wherein the stabilizer and/or inhibitor is 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide.

12. The resin mixture according to any one of claims 8 to 11, wherein the stable nitroxide radical is present in an amount of 0.02 to 1 wt %, based on the resin mixture.

13. The resin mixture according to any one of claims 8 to 11, wherein the table nitroxide radical is present in an amount of 0.05 to 25 wt %, based on the resin mixture.

14. The resin mixture according to any one of claims 8 to 13, wherein the radically polymerizable compound is obtained by reaction of di- and/or higher functional isocyanate with suitable acryl compounds, optionally with the participation of hydroxy compounds containing at least two hydroxyl groups.

15. The resin mixture according to any one of claims 8 to 14, which also contains at least one accelerator for curing the radically curable compound.

16. The reactive resin mortar containing a resin mixture according to any one of claims 8 to 15.

17. The reactive resin mortar according to claim 16, containing at least one inorganic additive selected from the group consisting of fillers, thickeners, thixotropy agents, nonreactive solvents, agents to improve flowability and/or wetting agents.

18. The reactive resin mortar according to claim 17, wherein the at least one inorganic additive is cement and/or quartz sand.

19. A multicomponent mortar system containing as the A component the reactive resin mortar according to any one of claims 16 to 18 and as the B component a hardener for the radically curable compound.

20. The multicomponent mortar system according to claim 19, wherein the A component additionally contains a hydraulically setting or polycondensable inorganic compound in addition to the reactive resin mortar, and the B component also contains water in addition to the hardener.

21. The use of the multicomponent mortar system according to claim 19 or 20 as a binder for chemical fastening.

22. The capsule or cartridge or film bag, comprising the multicomponent mortar system according to claim 19 or 20, wherein they comprise two or more separate chambers in which the reactive resin mortar and/or hardener is/are situated.

Description

EXEMPLARY EMBODIMENTS

A. Determination of Stability in Storage

Example 1 and Comparative Example 1

1a) Production of Resin Masterbatch

[0095] 688 g hydroxypropyl methacrylate is mixed with 0.5 mL dibutyltindilaurate. At 60 C. 311 g polymeric methylene diphenyl diisocyanate (pMDI; Desmodur VL R 20, maximum acidity value: 200 ppm HCl; Bayer) is added slowly by drops whereupon the internal temperature rises to 85 C. After the end of the dropwise addition, stirring is continued until the residual isocyanate content has dropped to less than 0.2%.

1b) Production of Resin Mixture

[0096] 698 g 1,4-butanediol dimethacrylate as the reactive diluent and 39 g bis(hydroxyethyl)-p-toluidine as the accelerator are added to the resulting resin masterbatch and the resin is stabilized with 9.8 g 2,6-di-tert-butyl-p-cresol and 0.7 g 2,3-dihydro-2,2-diphenyl-3-(phenyl-imino)-1H-indole-1-oxyl nitroxide as the stabilizer. By adding one or more aromatic amines, the pot life of the resin is set at approx. 7 min.

[0097] For comparison (Comparative Example 1; V1) instead of the 0.7 g 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide, 0.7 g 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl as the stabilizer.

[0098] Determination of the Stability of the Resin Mixtures in Storage

[0099] To simulate prolonged storage time, the samples were subjected to a thermostability test at an elevated temperature. In each case 20 mL of the resin sample (resin mixture) is welded in an oxygen-proof film (1117 cm) and then heated at a regulated 80 C. The sample is observed to ascertain whether gelation occurs during storage. The resulting perceptible increase in viscosity (consistency in gelation: ranging from similar to liquid honey to similar to gummy bears (gelatinous)) provides information about the thermal stability. Two independent double determinations were performed in each case. As a result the maximum time t at which the sample is not yet gelled is obtained, which yields the value for the stability in storage.

[0100] The resin mixture stabilized with 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide (Example 1) was stable for at least 248 hours and the resin mixture (V1) stabilized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl was stable for at least 48 hours.

[0101] As shown by these results, the time until gelation of a resin containing mineral acid can be increased by a factor of approximately five by addition of 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide as stabilizer.

Example 2 and Comparative Example 2

2) Production of Reactive Resin Mortar

[0102] The resin mixtures prepared as described above (Example 1, Comparative Example 1) were mixed with 30 to 45 wt % quartz sand, 15 to 25 wt % cement and 1 to 5 wt % pyrogenic silica in a dissolver to from a homogeneous mortar composition.

[0103] The stability of the reactive resin mortars in storage was determined as done with the resin mixtures.

[0104] Gelation occurred after about 68 hours in the case of the reactive resin mortar stabilized with 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide (Example 2) and after about 47 hours in the case of the reactive resin mortar stabilized with 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (Comparative Example 2, V2).

[0105] It has thus been demonstrated that it is also possible to increase the stability in storage of resin mixtures containing inorganic fillers, i.e., the reactive resin mortars on the basis of reactive resins containing traces of acid and thereby prolong the storage time.

B. Determination of the Pot Life and the Compound Stresses at Failure

Examples 3 and 4 as Well as Comparative Examples 3 and 4

3a) Production of the Reactive Resin Mortar (A-1)

[0106] To the resin masterbatch according to Example 1a) were added 698 g 1,4-butanediol dimethacrylate as the reactive diluent and 19.9 g N,N-bis(hydroxyethyl)-p-toluidine and 7.5 g 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide. A free-flowing preparation was prepared by mixing this with 50 g pyrogenic silica, 340 g alumina cement and 700 g quartz sand.

3b) Production of the Hardener Component (B)

[0107] To produce the hardener component 40 g dibenzoyl peroxide, 250 g water, 25 g pyrogenic silica, 5 g laminar silicate and 700 g quartz powder of a suitable grain size distribution were combined in the dissolver to form a homogeneous composition.

4) Production of Another Reactive [resin] Mortar (A-2)

[0108] 622 g of a commercial vinyl ester resin based on bisphenol A was combined with 510 g hydroxyethyl methacrylate and 568 g ethylene glycol dimethacrylate and 19.9 g N,N-bis(hydroxyethyl)-p-toluidine and 8.5 g 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide were added. A pasty composition was prepared by blending with 50 g pyrogenic silica, 340 g alumina cement and 700 g quartz sand.

5) Comparative Example 3 (V3)

[0109] For the comparison a reactive resin mortar according to Example 3a) was produced, except that instead of the 7.5 g 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide, 5.3 g 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl was used.

6) Comparative Example 4 (V4)

[0110] As a further comparison, a reactive resin mortar according to Example 3a) was prepared except that instead of the 7.5 g 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide, 5.4 g 2,6-di-tert-butyl-p-cresol was used.

[0111] Resin components (A-1) and (A-2) and also the hardener component (B) were mixed together in a volume ratio of 3:1, yielding mortar compositions.

[0112] Determination of the Pot Life of the Mortar Compositions

[0113] Determination of the pot life of mortar compositions obtained in this way was done using a commercial apparatus (GELNORM Gel Timer) at a temperature of 25 C. To do so, the components were mixed and heated with regulation in a silicone bath at 25 C. immediately after being mixed and the temperature of the sample was measured. The sample itself is in a test tube which is placed in an air blanket, and lowered into a silicone bath for temperature regulation.

[0114] The temperature of the sample was plotted as a function of time. The analysis was performed according to DIN 16945, Sheet 1 and DIN 16916. Pot life is the time when a temperature rise of 10K is achieved, namely here from 25 C. to 35 C.

[0115] Results of the pot life determinations are listed in Table 1.

[0116] Determination of the Composite Stresses at Failure

[0117] To determine the composite stresses at failure of the cured compound, threaded anchor rods M12, which were doweled into boreholes in concrete with a diameter of 14 mm and a borehole depth of 72 mm using the reactive resin mortar compositions of the examples and comparative examples. The average failure loads were determined by central extraction of the threaded anchor rods. Three threaded anchor rods were doweled into place in each case and their load values were determined after 24 hours of curing. The failure composite stresses (N/mm.sup.2) determined in this way are listed as the mean value in the following Table 1.

[0118] Various borehole conditions and/or curing conditions were tested as listed below.

TABLE-US-00001 Test condition Comment Reference well cleaned impact drilled borehole, curing at room temperature (+20 C.) 10 C. reference holes, setting and curing at an underground temperature of 10 C. +40 C. reference holes, setting and curing at an underground temperature of +40 C.

[0119] The results of the determination of the composite stresses at failure are also listed in Table 1.

TABLE-US-00002 TABLE 1 Results of the determination of the pot life and composite stresses at failure. Example 3 4 V3 V4 Pot life (25 C.) [min] 5:30 5:00 5:00 6:00 Stability in storage according >48 h >48 h <24 h <24 h to example 2 Composite stress at failure 10 C. 10.7 14.3 19.5 18.2 [N/mm.sup.2] +20 C. 20.7 21.3 20.9 21.0 +40 C. 23.2 23.5 21.5 22.9

[0120] It is apparent from this table that it is possible with 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide to adjust the pot life of a mortar composition in a targeted manner. In addition it has been shown that the composite stresses at failure are within the range of those of mortar compositions whose pot life was set at 5:00 min or 6:00 min using the known inhibitors 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl and 2,6-di-tert-butyl-p-cresol under reference conditions and at +40 C.

[0121] In storage, the same influence of oxygen on the pot life stability of the reactive resin mortars inhibited with 2,3-dihydro-2,2-diphenyl-3-(phenylimino)-1H-indole-1-oxyl nitroxide was also observed in the reactive resin mortars inhibited with 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl. This means that reactive resin mortars according to the invention stored in the absence of oxygen exhibit a gel time drift whereas reactive resin mortars according to the invention stored in the presence of oxygen do not.

[0122] It has thus been demonstrated that it has been possible to increase the stability in storage of resin mixtures as well as resin mixtures containing inorganic resin fillers based on reactive resins containing traces of oxygen and thereby significantly prolong the storage time. Furthermore, it has been shown that it is also possible to adjust the pot life using indole-nitroxide radicals.