POLYMERISABLE COMPOSITION COMPRISING TEMPO COMPOUND

Abstract

A polymerisable composition suitable for impregnating a permeable material, a process for the treatment of a permeable material, especially wood and an impregnated material is described. The composition includes at least 60% w/w composition of one or more polymerisable monomer(s) and an initiator effective to bulk polymerise the polymerisable monomers above 50 C. The composition includes up to 0.5% w/w tempo compound effective to stabilise the composition at temperatures less than 50 C. or below its thermally activated polymerisation temperature and to not substantially prevent polymerisation above the polymerisation temperature. The process has steps of locating the permeable material in a chamber; evacuating the chamber; adding a thermally initiatable bulk polymerisable composition to the chamber; allowing the material to become impregnated with polymerisable composition; removing excess polymerisable composition; and effecting bulk polymerisation of the composition by increasing the temperature of the impregnated material in the chamber to initiate polymerisation of the composition.

Claims

1. A polymerisable composition suitable for impregnating a permeable material comprising at least 60% w/w composition of one or more polymerisable monomer(s), and an initiator effective to bulk polymerise the polymerisable monomers above 50 C., wherein the polymerisable composition comprises up to 0.5% w/w tempo compound effective to stabilise the monomer composition at temperatures less than 50 C.

2. A process for treatment of a permeable material comprising the steps of: locating the permeable material in a chamber; evacuating the chamber to provide a vacuum effective to treat the permeable material in the said chamber; adding a thermally initiatable bulk polymerisable composition to the chamber; allowing the permeable material to become impregnated with the said polymerisable composition; removing excess polymerisable composition; effecting bulk polymerisation of the composition by increasing the temperature of the impregnated material in the chamber to initiate polymerisation of the composition; wherein the said polymerisable composition comprises at least 60% w/w composition of one or more polymerisable monomer(s) and an initiator effective to bulk polymerise the polymerisable monomers above 50 C., wherein the polymerisable composition also comprises up to 0.5% w/w tempo compound effective to stabilise the monomer composition at temperatures less than 50 C.

3. The process according to claim 2, wherein the bulk polymerisation is effected by heating the impregnated material between 50-100 C. to thermally initiate and polymerise the polymerisable composition by bulk polymerisation.

4. The process according to claim 2, wherein at least 80% mol/mol of the total tempo compound used in the bulk polymerisation reaction is present in the polymerisable composition at the commencement of the bulk polymerisation reaction.

5. The process according to claim 2, wherein excess polymerisable composition is stored at less than 50 C. before re-use and the excess polymerisable composition is stable at such temperatures.

6. A treatment plant for treatment of a permeable material, comprising a treatment vessel for treatment of the permeable material by impregnation with a polymerisable composition; a monomer storage tank comprising the said polymerisable composition; wherein the polymerisable composition comprises at least 60% w/w composition of one or more polymerisable monomer(s), and an initiator effective to polymerise the polymerisable monomers, wherein the polymerisable composition comprises up to 0.5% w/w tempo compound effective to stabilise the monomer composition at temperatures less than 50 C.

7. The plant according to claim 6, including a pressure evacuator effective to lower pressure in the treatment vessel to below 1 bar.

8. The polymerisable composition according to claim 1, wherein the composition comprises at least 60% w/w of one or more polymerisable monomer(s), wherein the polymerisable monomers are vinyl monomers.

9. The polymerisable composition according to claim 1, wherein the permeable material is wood.

10. The polymerisable composition according to claim 1, wherein the tempo compound is formula Ia ##STR00004## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl groups and hydrogen is not bound to the remaining valencies on the carbon atoms bound to nitrogen.

11. The polymerisable composition according to claim 10, wherein the alkyl groups R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are the same or different.

12. The polymerisable composition of claim 10, wherein the remaining valencies of the carbon atoms in the tempo compound which are not R.sup.1, R.sup.2, R.sup.3 and R.sup.4 or nitrogen are any atom or group except hydrogen which can bond covalently to carbon.

13. The polymerisable composition of claim 12, wherein the compound is according to formula Ic ##STR00005## wherein R.sup.5 and R.sup.6 are selected from hydrogen, C.sub.1 to C.sub.6 alkyl, acetamido, amino, 2-haloacetamido, carboxy, hydroxy, benzoate, isothiocyanate, maleimido, alkoxy, oxo, phosphonooxy, methacrylyloxy, methylsulfonyloxy, silyloxy, ethoxyfluorophosphonyloxy and 4-nitrobenzoyloxy; or R.sup.5 is an oligomer to which the rest of the compound is bound at the 4-position and R.sup.6 is hydrogen; R.sup.1 to R.sup.4 are selected from hydrogen or C.sub.1 to C.sub.12 alkyl; or R1 and/or R3 and/or R6 form a further ring or rings such that the tempo compound has a bicyclic or tricyclic structure; wherein halo means a halogen; wherein the term alkoxy means a C.sub.1 to C.sub.6 alkoxy group, and more than one tempo molecular moiety may be attached if there are multiple alkoxy bonds thereof; wherein the term aryl means C.sub.5 to C.sub.20 aryl.

14. The polymerisable composition of claim 13, wherein R.sup.6 is hydrogen or C.sub.1 to C.sub.6 alkyl and R.sup.5 is selected from hydrogen, acetamido, amino, 2-haloacetamido, carboxy, hydroxy, benzoate, isothiocyanate, maleimido, alkoxy, oxo, phosphonooxy, methacrylyloxy, methylsulfonyloxy, silyloxy, ethoxyfluorophosphonyloxy and 4-nitrobenzoyloxyl.

15. The polymerisable composition of claim 1, wherein the tempo compound is selected from 2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (CAS 2564-83-2), 4-hydroxyTEMPO and 4-acetamidoTEMPO.

16. The polymerisable composition of claim 1, wherein the one or more polymerisable monomer(s), are vinyl monomers selected from ethylene, styrene, acrylic monomers and combinations thereof.

17. The polymerisable composition according to claim 16, wherein the vinyl monomers are acrylic monomers selected from (alk)acrylic acids and esters thereof or mixtures thereof.

18. The polymerisable composition according to claim 17, wherein the acrylic monomers or mixtures thereof are selected from the type (Y)acrylic acids and X(Y)acrylate esters thereof where both X and Y may independently be linear or branched and are independently selected from alkyl, cycloalkyl, alkenyl, alkynyl or aryl groups which may contain heteroatoms.

19. The polymerisable composition according to claim 16, wherein the vinyl monomers other than acrylic monomers are selected from ethylene, styrene, vinyl pyrrolidinone and vinyl pyridine.

20. The polymerisable composition of claim 1, wherein the initiator is a thermally activated initiator.

21. The polymerisable composition of claim 1, wherein the initiators are thermally activated free radical initiators.

22. The polymerisable composition of claim 1, wherein the Initiators are free radical initiators selected from halogen compounds which may use transition metal co-catalysts, azo compounds organic peroxide compounds or inorganic peroxides.

23. The polymerisable composition of claim 1, wherein the initiator is present at up to 2% w/w composition.

24. The polymerisable composition of claim 1, wherein the monomer content is between 60-99.9% w/w composition.

25. The polymerisable composition of claim 1, wherein the tempo compound is present in the polymerisable composition.

26. The polymerisable composition of claim 1, wherein the tempo compound is present in the polymerisable composition at up to 0.3% w/w.

27. The polymerisable composition of claim 1, wherein there is at least 0.003% w/w tempo compound present in the polymerisable composition.

28. The polymerisable composition of claim 1, wherein a mol:mol ratio of tempo:initiator compound ranges from 1:1000 to 1:1.

29. The polymerisable composition of claim 1, wherein the tempo compound may be between 0.1 and 100 mol % of initiator.

30. The polymerisable composition of claim 1, wherein the tempo compound is present at 0.001 to 1 mol % composition.

31. An impregnated material comprising a polymerisable composition according to claim 1 that has been bulk polymerised.

32. (canceled)

33. The process of claim 2, wherein the permeable material is wood.

Description

EXAMPLES

Comparative Example 1

[0066] To exemplify this invention, we selected softwood as the Porous Material to be impregnation. Sections of scots pine (Pinus sylvestris) (1502121 mm) were dried at 60 C. for 16 hours in an unpressurised laboratory oven, weighed and loaded into an autoclave fitted with vacuum and a high pressure N.sub.2 supply. The pressure of the autoclave was reduced below ambient pressure using vacuum and maintained for 30 minutes. A 0.1% w/w solution of 1,1-azobis(2-methylpropionitrile) (Vazo 64; available from Arkema) in methyl methacrylate (Methyl Methacrylate 25TA; available from Lucite International and stabilised with 25 ppm 2,4-Dimethyl-6-tert-butylphenol commercially available as Topanol A from multiple commercial sources) was prepared and introduced to the vessel under vacuum such that the wood sections were submerged. The vacuum was maintained for a further 30 mins. The pressure in the vessel was then increased to 5 bar for 30 mins. Subsequently, the pressure was reduced to ambient levels and the vessel was drained. The impregnated pine sections were then wrapped in aluminium foil and transferred to an oven and heated to 75 C. for 16 hours. The weights of cured samples were recorded and PMMA levels (% w/w) calculated.

Example 1

[0067] The same process described in Comparative Example 1 was carried out with the addition of 260 ppm 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-Hydroxy-TEMPO; available from Sigma Aldrich) to the methyl methacrylate solution. The weights of cured samples were recorded and PMMA levels (% w/w) calculated. Levels of PMMA in the resulting cured composites from Comparative Example 1 and Example 1 are shown in Table 1

TABLE-US-00001 TABLE 1 Monomer mix composition Vazo 64 Composite Sample % w/w 4-Hydroxy-TEMPO/ppm % PMMA w/w I (Comparative 0.1 0 33.96 Example 1) II (Example 1) 0.1 260 29.97

Comparative Example 2

[0068] A 0.2% w/w solution of 1,1-azobis(2-methylpropionitrile) (Vazo 64; available from Arkema) in methyl methacrylate (Methyl Methacrylate 25TA; available from Lucite International containing 25 ppm Topanol A) was prepared. The solution was heated to 37 C. and maintained at that temperature. Small samples (0.5 g) of the solution were taken periodically and allowed to evaporate from a shallow dish at ambient temperature such that the % solids content could be determined to calculate degree of polymerisation. Complete gelation of the sample was observed after 7 days and was accompanied by exothermic autoacceleration which is consistent with the Trommsdorff effect indicating complete polymerisation.

Example 2

[0069] The same process described in Comparative Example 2 was carried out with the addition of 520 ppm 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl to the monomer solution. Small samples (0.5 g) of the solution were taken periodically and allowed to evaporate from a shallow dish at ambient temperature such that the % solids content could be determined to calculate degree of polymerisation. The monomer solution was observed to remain fluid up to 55 days at 37 C. with no rise in the % solids above 1%. No Trommsdorff effect was observed. The data showing % Solids against time for Comparative Example 2 and Example 2 are shown in FIG. 1.

[0070] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0071] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0072] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0073] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.