Abstract:
The present invention provides antifungal compositions based on Tetrabromobisphenol A (TBBA), its homologues and derivatives, that can be used to preserve wood. The invention provide a method for the preservation of wood against fungal attack, that employs the impregnation of wood with TBBA or its homologues and derivatives.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the preservation of timber. More particularly, the invention relates to the use of tetrabromobisphenol A and homologues and derivatives thereof, as a timber preservative.  
       BACKGROUND OF THE INVENTION  
       [0002]     Timber in use and in storage is prone to deterioration by a variety of micro-organisms but especially fungi such as basidiomycetes and moulds. It is therefore common to use chemical preservative treatments to prevent such biological deterioration and there are many different wood preservatives known in the art. Wood is stored and used in a variety of forms, such as blocks, plates, planks, and poles. The terms “timber” and “wood” are used interchangeably herein to indicate all forms of wood in need of protection against biological attack.  
         [0003]     Tetrabromobisphenol A (hereinafter referred to as “TBBA”) is a fire-retardant material widely employed in engineering plastics. It has been used in JP 61-6769 (Publication No. 55-159915, dated Dec. 12, 1980), to paint and coat a single plate which could then be preserved in the absence of mould growth. Although the antimicrobial activity of TBBA has been known for at least 20 years it has not yet found practical application in industry.  
         [0004]     Fungal attack of wood generally results in loss of the structural strength elements (indicated by weight loss in laboratory tests) and ultimately leads to mechanical failure of the timber structure. When, for instance, wooden utility poles are erected in the ground, fungal attack will eventually cause the breakage of the pole near ground level. The art has provided a number of preservative types used to prolong pole service life (such as Creosote and Copper Chrome Arsenate). However, these preservative types display disadvantages such as high volatile organic compound (VOC) emissions (Creosote) and high heavy metal contents (CCA).  
         [0005]     It is therefore an object of this invention to provide antifungal compositions based on TBBA, its homologues and derivatives, that can be used to preserve wood in the absence of the disadvantages inherent in other preserving compounds.  
         [0006]     It is another purpose of this invention to provide a method for the preservation of wood against fungal attack, that employs the impregnation of wood with TBBA or its homologues and derivatives.  
         [0007]     It is yet another purpose of the invention to provide a method and compositions that do not require the use of harmful solvents.  
         [0008]     Other purposes and advantages of the invention will appear as the description proceeds.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention relates to a fungicidal wood preservative comprising active ingredients which are Tetrabromobisphenol A (TBBA) [CAS RN=79-94-7] or a homologue or a derivative thereof. TBBA is the tetrabrominated form of Bisphenol A of formula  
                         
 
         [0010]     Where, for TBBA, R is C(CH 3 ) 2 .  
         [0011]     By “homologues” of TBBA it is meant to indicate those compounds in which the Bisphenol A bridge is replaced by a different moiety. Illustrative and non-limitative examples of such homologues include: 
        Tetrabromobisphenol F (TBBF), Bis(4-hydroxy-3,5-dibromophenyl)methane [CAS RN=21825-03-6], R is CH 2 ;     Tetrabromobisphenol Z (TBBZ), 4,4′-Cyclohexylidenebis(2,6-dibromophenol), [CAS RN=53350-96-2], R is  
                         
    Tetrabromobisphenol E (TBBE), 4,4′-Ethylidenebis(2,6-dibromophenol), [CAS RN=126369-25-3], R is CHCH 3 ; and     Tetrabromobisphenol S (TBBS), 4,4′-Sulfonyldi(2,6-dibromophenol), [CAS RN=39635-79-5], R is SO 2 .        
 
         [0016]     By “derivatives” of TBBA it is meant to indicate those compounds that are further substituted by a substituent other than bromine, either on one or both phenyl rings, or at the bridge. Any such substitutions that do not substantially alter the wood-preserving activity of the resulting compound with respect to TBBA are also encompassed by the present invention.  
         [0017]     Preferably, the compound employed is TBBA that has been solubilized in an organic or aqueous solvent. According to a preferred embodiment of the invention, the active compound is provided in aqueous solution. According to another preferred embodiment of the invention, the active compound is dissolved in an organic solvent such as alcohols, e.g. ethanol, hydrocarbons, toluene and ketones. According to a further preferred embodiment of the invention the active compound is incorporated in an emulsion.  
         [0018]     The present invention permits long-term preservation of wood without mould growth and protection against wood-destroying Basidiomycete fungi. The long-term preservation of wood is achieved by impregnating it with an active ingredient, e.g., TBBA, a derivative or a homologue of TBBA, or a mixture of two or more of the same, in an aqueous or organic solution or in an emulsion.  
         [0019]     A wood preservative comprising TBBA as the active ingredient in aqueous solution can be solubilized, for instance, by the addition of TBBA to a solution comprising water, sodium hydroxide (NaOH), and sodium dithionite (Na 2 S 2 O 4 ). The concentration of TBBA in solution (% by weight) may be in the range of 0.01% (W/W)-40% (W/W). More preferably, the concentration of TBBA may be in the range of 0.01% (W/W)-20% (W/W).  
         [0020]     The method for preserving wood comprises impregnating the wood by pressure-treatment with TBBA or its homologues and derivatives  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]     The above characteristics and advantages of the invention will be better understood through the following illustrative and non-limitative examples of preferred embodiments thereof.  
       Example 1  
     Biological Screening Test (Modified EN 113)  
       [0022]     The following fungi were employed in this test:  Coniophora puteana  (Brown rot fungus) and  Poria placenta  (Brown rot fungus). The following preservative was tested: TBBA (in ethanol carrier). Five concentrations of the preservative were used: 2%, 1%, 0.1%, 0.05% and 0.01% (w/w).  
         [0023]     All wood blocks employed in the examples to follow were of Scots pine sapwood ( Pinus sylvestris ) with a volume of 1 cm 3  (10 mm×10 mm×10 mm). Five replicate test specimens were used for each concentration of the preservative. Six virulence control specimens for each fungus were used to establish the wood decay capability of the fungi. Other test blocks were used to establish: the virulence of the test fungi; the absence of a preserving effect of the ethanol carrier; and weight changes of test blocks for reasons other than decay 
        Treated test specimens: 2 (fungi)×5 (preservative concentrations)×1 (preservative)×5 (replicates)=50 test blocks     Untreated test specimens (for exposure alongside treated blocks): one for each treated block=50 test blocks     Virulence control specimens: 2 (fungi)×6 (replicates)=12 test blocks     Ethanol carrier test specimens: 2 (fungi)×5 (replicates)=10 test blocks     Treated check test specimens: 1 (preservatives)×5 (concentrations)×5 (replicates)=25        
 
         [0029]     All timber specimens, where applicable, were treated with preservative (vacuum impregnation) and sterilized (ionizing radiation) prior to test, in accordance with European Standard EN 113. The incubation period for the test (length of block exposure to the chosen basidiomycete fungi) was 48 days or just under 7 weeks.  
         [0030]     It was noted in this modified test that waterlogging (above 180% moisture content) of certain of the test specimens had occurred, probably due to the small size of the test specimens. Weight changes for particular waterlogged specimens, when these are clearly unrepresentative of a group, are not included in the mean figures presented.  
         [0031]     Tables I and II show weight losses (% of initial dry weight) of TBBA treated and untreated control test specimens after 7 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
         [0032]     In the tables, “retention” refers to the quantity of preservative that enters the wood per cubic meter of treated wood. It&#39;s value is determined by weighing the block of wood before and after it is treated with preservative, taking the difference between the two weights, and dividing the difference in weight by the volume of the block.  
                                                           TABLE I                           TBBA            Concentrations                       of       compositions           Corrected   Mean loss in       studied       Retention   mean loss in   mass of       (% by weight)   Preservative   (kg/m 3 )   mass (%)   controls (%)                    2   TBBA   14.1 (0.63) (5)   No mass loss   33.92 (10.20)                       (5)       1   TBBA    6.7 (0.46) (5)    2.39 (1.56) (5)   31.43 (2.02) (5)       0.1   TBBA    0.7 (0.02) (5)   24.80 (—) (1)   26.37 (20.04)                       (3)       0.05   TBBA    0.4 (0.01) (5)   40.63 (7.59) (5)   29.94 (1.23) (5)       0.01   TBBA    0.1 (0.00) (5)   39.71(2.2) (4)   32.35(7.60) (3)                 Note:            All untreated control blocks were exposed alongside treated blocks.            Standard deviations and number of specimens selected for each mean are presented in parenthesis.             
 
         [0033]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE II 
               
             
             
               
                   
               
               
                   
               
               
                 TBBA 
               
             
          
           
               
                 Concentrations 
                   
                   
                   
                   
               
               
                 of compositions 
                   
                   
                 Corrected 
                 Mean loss in 
               
               
                 studied 
                   
                 Retention 
                 mean loss in 
                 mass of 
               
               
                 (% by weight) 
                 Preservative 
                 (kg/m 3 ) 
                 mass (%) 
                 controls (%) 
               
               
                   
               
             
          
           
               
                 2 
                 TBBA 
                 14.2 (0.48) (5) 
                  0.45 (1.48) (5) 
                  1.01 (3.04) (5) 
               
               
                 1 
                 TBBA 
                  6.9 (0.17) (5) 
                 No mass loss 
                 No mass loss 
               
               
                 0.1 
                 TBBA 
                  0.7 (0.05) (5) 
                 26.67(11.04) 
                 37.89 (7.52) (2) 
               
               
                   
                   
                   
                 (3) 
               
               
                 0.05 
                 TBBA 
                  0.4 (0.02) (5) 
                  4.84 (0.32) (5) 
                 11.03 (—) (1) 
               
               
                 0.01 
                 TBBA 
                  0.1 (0.00) (5) 
                  0.88 (0.29) (5) 
                 No mass loss 
               
               
                   
               
               
                   Note:    
               
               
                   All untreated control blocks were exposed alongside treated blocks.    
               
               
                   Standard deviations and number of specimens selected for each mean are presented in parenthesis.    
               
             
          
         
       
     
         [0034]     Tables III and IV show weight losses (% of initial dry weight) of untreated virulence control specimens after 7 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                                     TABLE III                           Loss in mass of           Specimen Numbers   Virulence controls (%)   Mean loss in mass (%)                                301   28.88   22.52 (7.38)       302   30.59       303   17.33       304   13.56       305   30.89       306   21.95                 Note:            Standard deviation in parenthesis.             
 
         [0035]    
       
         
               
               
               
             
           
               
                 TABLE IV 
               
               
                   
               
               
                   
               
               
                   
                 Loss in mass of 
                   
               
               
                 Specimen Numbers 
                 Virulence controls (%) 
                 Mean loss in mass (%) 
               
               
                   
               
             
             
               
                 307 
                 No mass loss 
                 Not calculated 
               
               
                 308 
                 10.22 
               
               
                 309 
                 No mass loss 
               
               
                 310 
                 No mass loss 
               
               
                 311 
                 No mass loss 
               
               
                 312 
                 No mass loss 
               
               
                   
               
             
          
         
       
     
         [0036]     Tables V and VI show weight losses (% of initial dry weight) of ethanol carrier control specimens after 7 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                             TABLE V                           TBBA                Loss in mass of           Specimen Numbers   Ethanol controls (%)   Mean loss in mass (%)               319    1.19   26.09 (9.00) (4)       320   13.67       321   34.76       322   26.14       323   29.80                 Note:            Standard deviation and number of specimens selected for the mean presented in parenthesis.             
 
         [0037]    
       
         
               
             
               
               
               
             
           
               
                 TABLE VI 
               
             
             
               
                   
               
               
                   
               
               
                 TBBA 
               
             
          
           
               
                   
                 Loss in mass of 
                   
               
               
                 Specimen Numbers 
                 Ethanol controls (%) 
                 Mean loss in mass (%) 
               
               
                   
               
               
                 324 
                 No mass loss 
                 No mass loss 
               
               
                 325 
                 No mass loss 
               
               
                 326 
                 No mass loss 
               
               
                 327 
                 No mass loss 
               
               
                 328 
                 No mass loss 
               
               
                   
               
             
          
         
       
     
         [0038]     The decay basidiomycete  Coniophora puteana  displayed a high degree of virulence during the test period (Table III) and was not affected by the ethanol carrier (Table V). The results shown in Table I, indicate that only specimens treated to the highest mean retention of 14.1 kg/m 3  with TBBA displayed no weight loss. The mean weight loss of 2.39% recorded for specimens treated to a retention 6.7 kg/m 3  with TBBA includes a figure of 4.77. The effect of waterlogging was minimal in this section of the test.  
         [0039]     For  Poria placenta  the effect of waterlogging served to prevent the recording of any useful data from the virulence and carrier control tests (Tables IV and VI). The absence of decay in these tests is normally used to ascertain the validity of the remaining test results (shown in Table II). However, significant mean weight losses were recorded for several untreated and TBBA treated specimens (Table II) confirming that the absence of data from the virulence and carrier control tests was most likely due to waterlogging. The results shown in Table II indicate that specimens treated to mean TBBA retentions of 6.9 and 14.2 kg/m 3  displayed no weight loss while specimens treated to 0.7 kg/m 3  displayed a mean weight loss of 26.67%. Though waterlogging influenced the results of this test to some extent, the absence of waterlogging in TBBA treated specimens at the two highest retentions and the mass loss shown by waterlogged treated specimens at 0.7 kg/m 3  gives confidence in the results (Table II).  
       Example 2  
     Penetration of TBBA into Timber Via Impregnation  
       [0040]     An aqueous TBBA solution of 20.16% (w/w) was prepared by dissolving 217.5 g TBBA in 800 g H 2 O, containing 33.6 g NaOH and 4 g Na 2 S 2 O 4 .  
         [0041]     The solution was stirred for 10 min at 45° C. Sample specimens consisting of 6 oven-dried sapwood blocks of Scots pine ( Pinus sylvestris ) measuring 20×20×20 mm were vacuum impregnated with the solution according to the methodology of the European standard EN 113. TBBA uptake into the blocks is shown in Table VII. Two further blocks of identical dimensions were vacuum impregnated with de-ionized water to serve as controls.  
                                                   TABLE VII                           TBBA            Block No.   Block Dry Wt. (g)   Uptake Wt. (g)   TBBA Uptake (mg)                    1   3.19   8.64   1,100       2   4.12   10.62   1,311       3   3.82   9.36   1,115       4   3.38   8.90   1,113       5   3.28   9.22   1,197       6   3.05   9.84   1,369                  
 
         [0042]     The treated blocks were rapidly air-dried in the laboratory. Sawdust samples were recovered for TBBA extraction by hand-sanding the 6 faces of each of the 6 treated blocks for 30 seconds removing timber to an approximate depth of 0.75 mm on each occasion. This procedure was undertaken 4 times. New laboratory gloves and sandpaper were used for each sanding to negate contamination between the samples. This procedure provided 4 sawdust samples, as follows: 
        Sample 1: Representing 0-0.75 mm depth     Sample 2: Representing 0.75-1.5 mm depth     Sample 3: Representing 1.5-2.25 mm depth     Sample 4: Representing 2.25-3 mm depth.        
 
         [0047]     The total volume of these samples equates to 65.7% of the total volume of the test blocks. A similar procedure was undertaken for the control blocks, but for these blocks, a surface sample (0-0.75 mm) only was removed.  
         [0048]     Each sawdust sample was placed in a conical flask (125 cm 3 ). De-ionized water (20 cm 3 ) was added to each flask. The flasks were heated at 65° C. for precisely 1 hour. The contents of each flask were filtered (Whatman No. 1) into beakers and the filtered sawdust samples were discarded. The filtered solutions were brought to a pH of 5-6 using dilute hydrochloric acid added drop-wise (checked with pH paper). The contents of each beaker were thoroughly mixed throughout this addition procedure. A heavy precipitate was noted in the base of all the beakers except that containing the control blocks extracts (this last was discarded). The beakers were covered and left to stand. After 16 hours the supernatant was drained off from the 4 beakers containing precipitate and the remaining precipitate dried in an oven at 40° C. The dried precipitates were then dissolved in acetonitrile (20 cm 3 ) and the solutions were filtered to remove any remaining undissolved precipitate. This procedure provided 4 clear solutions for High-Performance Liquid Chromatography (HPLC) analysis.  
       Example 3  
     Biological Efficacy Test (EN 113)  
       [0049]     Two fungi were used:  Coniophora puteana  Brown rot fungus) and  Poria placenta  (Brown rot fungus). The preservative used was TBBA (waterborne). Seven concentrations of the preservative was used: 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.05%, and 0.0% (w/w), i.e. the carrier solution in the absence of the active material. All wood blocks were of Scots pine sapwood ( Pinus sylvestris ) with an approximate volume of 18.75 cm 3  (50 mm×25 mm×15 mm) in accordance with European standard EN 113. 
        Treated test specimens: 2 (fungi)×7 (preservative concentrations)×1 (preservative)×4 (replicates)=56 test blocks     Untreated test specimens (for exposure alongside treated blocks): 2 (fungi)×7 (preservative concentrations)×1 (preservative)×4 (replicates)=56 test blocks     Untreated test specimens (virulence): 2 (fungi)×6 (replicates)=12 test blocks     Treated check test specimens: 4 (replicates)×7 (preservative concentrations)×1 (preservative)=28 test blocks        
 
         [0054]     After block impregnation, according to European standard EN 113, and conditioning were completed, all the blocks were sterilized using ionizing radiation according to the conditions set out in EN 113. The incubation period for the test (length of block exposure to the chosen basidiomycete fungi) was 16 weeks.  
         [0055]     It was noted that some waterlogging of certain test and control specimens had occurred. In keeping with the EN 113 format, weight changes for particular waterlogged specimens, when these are clearly unrepresentative of a group, were not included in the mean figures presented. In addition, weight losses of unrepresentative specimens generally, were not included in the mean figures presented.  
         [0056]     Table VIII shows weight losses (% of initial dry weight) of TBBA treated, untreated control and virulence control test specimens after 16 weeks exposure to  Coniophora puteana  on an agar medium (EN 113).  
                                               TABLE VIII                           TBBA            Concen-                       trations                       of                       compo-                       sitions                       studied           Corrected   Mean loss in       (% by    Retention   Specimen   mean loss in   mass of       weight)   (kg/m 3 )   Numbers   mass (%)   controls (%)               3.0   23.65 (1.43)   1-4   −1.06 (0.69)   48.61 (4.37)       2.0   15.24 (1.56)   13-16   −6.79 (0.34)   54.72 (8.50)       1.5   11.12 (0.79)   25-28   −1.30 (1.16)   63.51 (1.00)       1.0    7.30 (0.26)   37-40   37.27 (—)   57.35 (5.75)       0.5    3.78 (0.10)   49-52   34.87 (13.21)   46.93 (8.84)       0.05     0.39 (0.01)   61-64   46.82 (6.31)   47.78 (11.83)       0.0    0.00   73-76   41.94 (7.62)   45.28 (5.83)            Mean loss in mass (%) of virulence control specimens:   48.34 (6.48)                 Note:            All untreated control blocks were exposed alongside treated blocks. Standard deviations for each mean are presented in parenthesis.            Means have been adjusted for outlying values.             
 
         [0057]     Table IX shows weight losses (% of initial dry weight) of TBBA treated, untreated control and virulence control test specimens after 16 weeks exposure to  Poria placenta  on an agar medium (EN 113).  
                                               TABLE IX                           TBBA            Concentrations                       of       compositions               Mean loss in       studied   Retention       Corrected mean   mass of controls       (% by weight)   (kg/m 3 )   Specimen Numbers   loss in mass (%)   (%)               3.0   20.70 (5.39)   5-8   −1.67 (0.22)   29.36 (—)       2.0   12.84 (4.60)   17-20   −6.21 (0.44)   46.17 (—)       1.5   11.81 (0.47)   29-32   −2.19 (070)   47.29 (6.19)       1.0    7.71 (0.19)   41-44    6.17 (14.50)   43.54 (2.19)       0.5    3.79 (0.15)   53-56    7.94 (19.35)   32.95 (12.47)        0.05    0.25 (0.28)   65-68   30.94 (2.90)   30.85 (5.62)       0.0    0.00   77-80   30.23 (4.37)   32.41 (4.16)            Mean loss in mass (%) of virulence control specimens:   29.19 (14.28)                 Note:            All untreated control blocks were exposed alongside treated blocks.            Standard deviations for each mean are presented in parenthesis.            Means have been adjusted for outlying values.             
 
         [0058]     The decay basidiomycete  Coniophora puteana  displayed a high degree of virulence against untreated virulence control specimens resulting in a mean weight loss of 48.3% (Table VIII). These weight losses were well in excess of the minimum 20% weight loss required to validate the test for this organism. In addition, the mean loss in mass of control specimens (incubated alongside treated specimens) was consistently high indicating good decay conditions within each culture vessel.  
         [0059]      Coniophora puteana +TBBA: Table VIII shows that specimens treated with TBBA to retentions of 11.12 kg/m 3  and upwards displayed no weight loss. These retentions therefore afforded satisfactory protection to the timber under the conditions of this test. Specimens treated with TBBA to retentions of 7.30 kg/m 3  and below did not afford satisfactory protection to the timber samples. The toxic values of TBBA with respect to  Coniophora puteana  therefore lie between 7.30 and 11.12 kg/m 3 .  
         [0060]     The decay basidiomycete  Poria placenta  displayed a high degree of virulence against untreated virulence control specimens resulting in a mean weight loss of 29.2% (Table IX).  
         [0061]      Poria placenta +TBBA: Table IX shows that specimens treated with TBBA to retentions of 11.81 kg/m 3  and upwards display no weight loss.  
         [0062]     These retentions therefore afford satisfactory protection to the timber under the conditions of this test. Specimens treated with TBBA to retentions of 7.71 kg/m 3  and below do not afford satisfactory protection to the timber samples. The toxic values of TBBA with respect to  Poria placenta  therefore lie between 7.71 and 11.81 kg/m3.  
       Example 4  
     Biological Efficacy Test (ASTM D1413-76)  
       [0063]     The following fungi were tested:  Neo - Lentinus lepideus  (Brown rot fungus),  Poria placenta  (Brown rot fungus) and  Gloeophyllum trabeum  (Brown rot fungus). The preservative used was TBBA (waterborne). Seven concentrations of the preservative was used: 3.0%, 2.0%, 1.5%, 1.0%, 0.5%, 0.05% and 0.0% (w/w), i.e. the carrier solution in the absence of the preservative. All wood blocks were of Scots pine sapwood ( Pinus sylvestris ) with an approximate volume of 6.86 cm 3  (19 mm×19 mm×19 mm). All wood block specimens, where applicable, were vacuum impregnated with the preservative concentrations according to American standard ASTM D1413-76. 
        Treated test specimens: 3 (fungi)×7 (preservative concentrations)×1 (preservative)×8 (replicates)=168 test blocks     Untreated test specimens (control): 3 (fungi)×1 (preservative)×4 (replicates)=12 test blocks        
 
         [0066]     After block treatments were completed, all the blocks were sterilized using ionizing radiation according to the conditions set out in American standard ASTM D1413-76. The incubation period for the test was 12 weeks.  
         [0067]     Table X shows weight losses (% of initial conditioned dry weight) of TBBA treated and control specimens after 12 weeks exposure to  Neo - Lentinus lepideus  on a soil block medium (ASTM D1413-76).  
                                                           TABLE X                           TBBA            Concentrations                       of compositions               Mean loss in       studied   Retention       Corrected mean   mass of controls       (% by weight)   (kg/m 3 )   Specimen Numbers   loss in mass (%)   (%)                    3.0   23.79 (0.72)   1-8    0.11 (0.38)   29.75 (6.76)       2.0   15.51 (0.35)   25-32    0.04 (0.20)       1.5   11.61 (0.53)   49-56    0.04 (0.09)       1.0    7.62 (0.19)   73-80    0.36 (0.19)       0.5    3.86 (0.12)    97-104    4.55 (16.26)       0.05    0.40 (0.01)   121-128   31.44 (5.65)       0.0    0.00   145-152   22.67 (8.84)                 Note:            Standard deviations for each mean are presented in parenthesis.             
 
         [0068]     Table XI shows weight losses (% of initial conditioned dry weight) of TBBA treated and control test specimens after 12 weeks exposure to  Poria placenta  on a soil block medium (ASTM D1413-76).  
                                                           TABLE XI                           TBBA            Concentrations of                       compositions               Mean loss       studied   Retention   Specimen   Corrected mean   in mass of controls       (% by weight)   (kg/m 3 )   Numbers   loss in mass (%)   (%)                    3.0   23.22 (0.85)     9-16   −0.71 (0.14)   27.06 (7.51)       2.0   15.72 (0.47)    33-40   −0.29 (0.26)       1.5   11.57 (0.40)    57-64   −0.12 (0.28)       1.0   7.81 (0.26)   81-88    9.65 (18.03)       0.5   3.86 (0.05)   105-112   30.27 (5.59)       0.05   0.38 (0.01)   129-136   31.70 (9.88)       0.0   0.00   153-160   23.48 (5.07)                 Note:            Standard deviations for each mean are presented in parenthesis.             
 
         [0069]     Table XII shows weight losses (% of initial conditioned dry weight) of TBBA treated and control test specimens after 12 weeks exposure to  Gloeophyllum trabeum  on a soil block medium (ASTM D1413-76).  
                                                           TABLE XII                           TBBA            Concentrations of                       compositions           Corrected           studied   Retention   Specimen   mean loss in mass   Mean loss in mass       (% by weight)   (kg/m 3 )   Numbers   (%)   of controls (%)                    3.0   23.02 (0.85)    17-24   0.13 (0.26)   41.06 (12.74)       2.0   15.62 (0.33)    41-48   0.29 (0.25)       1.5   11.75 (0.26)    65-72   2.232 (4.66)        1.0   7.73 (0.17)   89-96   5.52 (8.99)       0.5   3.87 (0.15)   113-120   45.02 (7.20)        0.05   0.38 (0.14)   137-144   42.71 (13.14)       0.0   0.00   161-168   45.11 (14.46)                 Note:            Standard deviations for each mean are presented in parenthesis.             
 
         [0070]     The decay basidiomycete  Neo - Lentinus lepideus  displayed a high degree of virulence against untreated control specimens resulting in a mean weight loss of 29.7% (Table X).  
         [0071]      Neo - Lentinus lepideus +TBBA: Table X shows that specimens treated with TBBA to retentions of 7.62 kg/m 3  and upwards displayed no significant weight loss. These retentions therefore afforded satisfactory protection to the timber under the conditions of this test. Specimens treated with TBBA to retentions of 3.86 kg/m 3  and below were not protected. The threshold retention of TBBA in respect of  Neo - Lentinus lepideus  therefore lies between 3.86 and 7.62 kg/m 3 .  
         [0072]      Poria placenta +TBBA: The decay basidiomycete  Poria placenta  displayed a high degree of virulence against untreated control specimens resulting in a mean weight loss of 27.0% (Table XI).  
         [0073]     Table XI shows that specimens treated with TBBA to retentions of 11.57 kg/m 3  and upwards displayed no weight loss. These retentions therefore afforded satisfactory protection to the timber under the conditions of this test. Specimens treated with TBBA to retentions of up to 7.81 kg/m 3  did not afford satisfactory protection to the timber samples. The threshold retention of TBBA in respect of  Poria placenta  therefore lies between 7.81 and 11.57 kg/m 3 .  
         [0074]      Gloeophyllum trabeum +TBBA: The decay basidiomycete  Gloeophyllum trabeum  displayed a high degree of virulence against untreated control specimens resulting in a mean weight loss of 41.0% (Table XII).  
         [0075]     Table XII shows that specimens treated with TBBA to retentions of 15.62 kg/m 3  and upwards displayed no significant weight loss. These retentions therefore afforded satisfactory protection to the timber under the conditions of this test. Specimens treated with TBBA to retentions of up to 11.75 kg/m 3  did not afford satisfactory protection to the timber samples. The threshold retention of TBBA in respect of  Gloeophyllum trabeum  therefore lies between 11.75 and 15.62 kg/m 3 .  
       Example 5  
     Biological Screening Test (Modified EN 113)  
       [0076]     The following fungi were employed:  Coniophora puteana  (Brown rot fungus) and  Poria placenta  (Brown rot fungus). The following preservatives were tested: TBBF (waterborne), TBBE (waterborne), TBBZ (waterborne) and TBBS (waterborne).  
         [0077]     Five concentrations of each preservative were tested: 3.0%, 2.0%, 1.0%, 0.1% and 0.05% (w/w). All wood blocks were of Scots pine sapwood ( Pinus sylvestris ) with a volume of 1 cm 3  (10 mm×10 mm×10 mm). Five replicates were used for each test specimen type and six virulence control specimens for each fungus and for each preservative were used as follows: 
        Treated test specimens: 2 (fungi)×5 (preservative concentrations)×1 (preservative)×5 (replicates)=50 test blocks     Untreated test specimens (for exposure alongside untreated test blocks): 2 (fungi)×5 (preservative concentrations)×1 (preservative)×5 (replicates)=50 test blocks     Treated check test specimens: 1 (preservative)×5 (concentrations)×5 (replicates)=25 blocks        
 
         [0081]     For all actives/preservatives in the test: 
        Virulence control specimens: 2 (fungi)×6 (replicates)=12 test blocks        
 
         [0083]     After block treatments were completed, all the blocks were sterilized using ionizing radiation according to the conditions set out in European standard EN 113. The incubation period for the test (length of block exposure to the chosen basidiomycete fungi) was 8 weeks.  
         [0084]     It was noted in this modified test that waterlogging (180% moisture content and above) of a number of the test specimens had occurred. Weight changes for particular waterlogged specimens, when these were clearly unrepresentative of a group, were not included in the mean figures presented. In addition, weight losses of unrepresentative specimens generally, were not included in the mean figures presented (note that “unrepresentative”, in this context, does not refer to very high weight loss figures, as these cannot be discarded).  
         [0085]     Tables XIII and XIV show weight losses (% of initial dry weight) of TBBF treated test specimens after 8 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                                                   TABLE XIII                           TBBF            Concentrations of                   compositions       studied   Retention   Corrected mean   Mean loss in mass       (% by weight)   (kg/m 3 )   loss in mass (%)   of controls (%)                    3.0   23.1 (2.07)    No Decay   30.51 (7.04)       2.0   15.1 (1.35)    No Decay    12.06 (11.49)       1.0   7.9 (0.36)   No Decay   37.00 (6.13)       0.1   0.8 (0.02)   24.49 (2.12) (W)   30.82 (1.73)       0.05   0.4 (0.02)   26.87 (7.38)   29.50 (4.21)                 Note:            Standard deviations are presented in parenthesis.            W: Some Waterlogging.             
 
         [0086]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE XIV 
               
             
             
               
                   
               
               
                   
               
               
                 TBBF 
               
             
          
           
               
                 Concentrations of 
                   
                   
                   
               
               
                 compositions 
                   
                 Corrected 
               
               
                 studied 
                 Retention 
                 mean loss in 
                 Mean loss in 
               
               
                 (% by weight) 
                 (kg/m 3 ) 
                 mass (%) 
                 mass of controls (%) 
               
               
                   
               
             
          
           
               
                 3.0 
                 20.8 (4.27)  
                 No Decay 
                 No Decay 
               
               
                 2.0 
                 15.7 (0.83)  
                 No Decay 
                 49.54 (—) 
               
               
                 1.0 
                 7.7 (0.59) 
                 No Decay 
                 36.67 (14.24) 
               
               
                 0.1 
                 0.8 (0.02) 
                 20.90 (0.23) 
                 25.25 (9.67) 
               
               
                 0.05 
                 0.4 (0.11) 
                 24.20 (9.63) 
                 11.16 (23.82) 
               
               
                   
               
               
                   Note:    
               
               
                   Standard deviations are presented in parenthesis.    
               
             
          
         
       
     
         [0087]     Tables XV and XVI show weight losses (% of initial dry weight) of TBBE treated test specimens after 8 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                                                   TABLE XV                           TBBE            Concentrations of                   compositions       Corrected       studied   Retention   mean loss in   Mean loss in       (% by weight)   (kg/m 3 )   mass (%)   mass of controls (%)                    3.0   24.7 (0.64)    No Decay   29.79 (3.30)       2.0   14.7 (1.56)    No Decay   31.38 (1.18)       1.0   7.9 (0.43)   No Decay    31.88 (10.29)       0.1   0.7 (0.26)   26.57 (2.99)   28.34 (6.43)       0.05   0.4 (0.01)   22.96 (4.81)    25.92 (13.81)                 Note:            Standard deviations are presented in parenthesis.             
 
         [0088]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE XVI 
               
             
             
               
                   
               
               
                   
               
               
                 TBBE 
               
             
          
           
               
                 Concentrations of 
                   
                   
                   
               
               
                 compositions 
               
               
                 studied 
                 Retention 
                 Corrected mean 
                 Mean loss in 
               
               
                 (% by weight) 
                 (kg/m 3 ) 
                 loss in mass (%) 
                 mass of controls (%) 
               
               
                   
               
             
          
           
               
                 3.0 
                 24.6 (0.58)  
                 No Decay 
                  4.14 (11.18) 
               
               
                 2.0 
                 14.4 (2.16)  
                 No Decay (W) 
                 20.04 (11.36) 
               
               
                 1.0 
                 8.3 (0.33) 
                 No Decay (W) 
                 No Decay 
               
               
                 0.1 
                 0.8 (0.01) 
                 28.67 (14.13) 
                 25.01 (18.64) 
               
               
                 0.05 
                 0.4 (0.04) 
                 No Decay (0.89) 
                 13.49 (11.02) 
               
               
                   
               
               
                   Note:    
               
               
                   Standard deviations are presented in parenthesis.    
               
               
                   W: Some Waterlogging.    
               
             
          
         
       
     
         [0089]     Tables XVII and XVIII show weight losses (% of initial dry weight) of TBBZ treated test specimens after 8 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                                                   TABLE XVII                           TBBZ            Concentrations of                   compositions       studied   Retention   Corrected mean   Mean loss in       (% by weight)   (kg/m 3 )   loss in mass (%)   mass of controls (%)                    3.0   17.6 (2.54)    No Decay    15.61 (14.09)       2.0   11.8 (2.51)    No Decay    21.55 (12.21)       1.0   6.8 (0.64)   14.30 (—)   35.96 (6.39)       0.1   0.7 (0.06)   34.44 (2.42   26.64 (9.00)       0.05   0.4 (0.02)   33.57 (7.59) (W)   29.72 (5.54)                 Note:            Standard deviations are presented in parenthesis.            W: Some Waterlogging.             
 
         [0090]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE XVIII 
               
             
             
               
                   
               
               
                   
               
               
                 TBBZ 
               
             
          
           
               
                 Concentrations of 
                   
                   
                   
               
               
                 compositions 
               
               
                 studied 
                 Retention 
                 Corrected mean 
                 Mean loss in 
               
               
                 (% by weight) 
                 (kg/m 3 ) 
                 loss in mass (%) 
                 mass of controls (%) 
               
               
                   
               
             
          
           
               
                 3.0 
                 18.6 (3.41)  
                 No Decay 
                 5.14 (9.79) 
               
               
                 2.0 
                 11.6 (1.45)  
                 No Decay 
                 0.13 (1.35) 
               
               
                 1.0 
                 5.9 (3.04) 
                 No Decay 
                 12.74 (21.19) 
               
               
                 0.1 
                 0.8 (0.05) 
                 33.47 (15.74) 
                 22.84 (15.25) 
               
               
                 0.05 
                 0.4 (0.01) 
                  0.94 (3.19) (W) 
                 45.31 (13.20) 
               
               
                   
               
               
                   Note:    
               
               
                   Standard deviations are presented in parenthesis.    
               
               
                   W: Some Waterlogging.    
               
             
          
         
       
     
         [0091]     Tables XIX and XX show weight losses (% of initial dry weight) of TBBS treated test specimens after 8 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                                                   TABLE XIX                           TBBS            Concentrations of                   compositions       Corrected       studied   Retention   mean loss in   Mean loss in       (% by weight)   (kg/m 3 )   mass (%)   mass of controls (%)                    3.0   20.2 (6.54)    No Decay   28.61 (3.46)       2.0   16.1 (0.79)    No Decay   32.20 (6.54)       1.0   7.6 (0.83)   No Decay   38.42 (2.63)       0.1   0.8 (0.02)   35.49 (4.92)   34.61 (2.02)       0.05   0.4 (0.04)   35.02 (6.61)   36.59 (4.41)                 Note:            Standard deviations are presented in parenthesis.             
 
         [0092]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE XX 
               
             
             
               
                   
               
               
                   
               
               
                 TBBS 
               
             
          
           
               
                 Concentrations of 
                   
                   
                   
               
               
                 compositions 
                   
                 Corrected 
               
               
                 studied 
                 Retention 
                 mean loss in 
                 Mean loss in 
               
               
                 (% by weight) 
                 (kg/m 3 ) 
                 mass (%) 
                 mass of controls (%) 
               
               
                   
               
             
          
           
               
                 3.0 
                 25.0 (0.46)  
                 No Decay 
                 34.45 (4.00)  
               
               
                 2.0 
                 15.3 (1.48)  
                 No Decay 
                 32.43 (17.48) 
               
               
                 1.0 
                 7.9 (1.13) 
                 No Decay 
                 11.75 (27.33) 
               
               
                 0.1 
                 0.8 (0.10) 
                 No Decay 
                 12.02 (24.51) 
               
               
                 0.05 
                 0.4 (0.01) 
                 No Decay 
                 2.13 (0.78) 
               
               
                   
               
               
                   Note:    
               
               
                   Standard deviations are presented in parenthesis.    
               
             
          
         
       
     
         [0093]     Tables XXI and XXII show weight losses (% of initial dry weight) of untreated virulence control specimens after 8 weeks exposure to  Coniophora puteana  and  Poria placenta  respectively.  
                       TABLE XXI                       Specimen   Loss in   Mean loss in       Number   mass (%)   mass (%)                   1226   25.91           1227   27.95       1228   34.74   32.40 (4.35)       1229   34.02       1230   36.18       1231   35.61                 Note:            All untreated control blocks were exposed alongside treated blocks.            Standard deviations are presented in parenthesis.             
 
         [0094]    
       
         
               
               
               
             
           
               
                 TABLE XXII 
               
               
                   
               
               
                   
               
               
                 Specimen 
                 Loss in 
                 Mean loss in 
               
               
                 Number 
                 mass (%) 
                 mass (%) 
               
               
                   
               
             
             
               
                 1232 
                 No Decay 
                   
               
               
                 1233 
                 No Decay 
               
               
                 1234 
                 No Decay 
               
               
                 1235 
                 No Decay 
               
               
                 1236 
                 No Decay 
               
               
                 1237 
                 8.30 
               
               
                   
               
               
                   Note:    
               
               
                   All untreated control blocks were exposed alongside treated blocks.    
               
               
                   Standard deviations are presented in parenthesis.    
               
             
          
         
       
     
         [0095]     The decay basidiomycete  Coniophora puteana  displayed a high degree of virulence during the test period (Table XXI). This is confirmed by the generally excellent weight losses for untreated control specimens throughout the test (Tables XIII-XIX).  
         [0096]     Table XIII indicates that test specimens treated with TBBF to a retention of between 0.8 and 7.9 kg/m 3  will provide a protective effect against  Coniophora puteana  (under the conditions of this test).  
         [0097]     Table XV indicates that test specimens treated with TBBE to a retention of between 0.7 and 7.9 kg/m 3  will provide a protective effect against  Coniophora puteana  (under the conditions of this test).  
         [0098]     Table XVII indicates that test specimens treated with TBBZ to a retention between 0.7 and 6.8 kg/m 3  will provide a protective effect against  Coniophora puteana  (under the conditions of this test).  
         [0099]     Table XIX indicates that test specimens treated with TBBS to a retention between 0.8 and 7.6 kg/m 3  will provide a protective effect against  Coniophora puteana  (under the conditions of this test).  
         [0100]     Overall results for  Coniophora puteana  can be summarised as follows, where the protective effect is expressed in terms of the retention of the active ingredient in the wood followed in parenthesis by the concentration of the active ingredient in solution. 
        TBBF: Protective Effect=0.8-7.9 kg/m 3  (=&gt;0.1-1.0%)     TBBE: Protective Effect=0.7-7.9 kg/m 3  (=&gt;0.1-1.0%)     TBBZ: Protective Effect=0.7-6.8 kg/m 3  (=&gt;0.1-1.0%)     TBBS: Protective Effect=0.8-7.6 kg/m 3  (=&gt;0.1-1.0%)        
 
         [0105]     The virulence control specimen results for the decay basidiomycete  Poria placenta  indicate that this basidiomycete displayed a low degree of virulence during the test period (Table XXII). However, the variability in weight losses due to this basidiomycete for untreated control specimens throughout the test (Tables XIV-XX) indicate that, though the organism failed to establish itself completely, where this occurred, weight losses were of an order that the virulence of the organism was not in doubt.  
         [0106]     Table XIV indicates that test specimens treated with TBBF to a retention of between 0.8 and 7.7 kg/m 3  will provide a protective effect against  Poria placenta  (under the conditions of this test).  
         [0107]     Table XVI indicates that test specimens treated with TBBE to a retention of between 0.8 and 8.3 kg/m 3  will provide a protective effect against  Poria placenta  (under the conditions of this test).  
         [0108]     Table XVIII indicates that test specimens treated with TBBZ to a retention between 0.8 and 5.9 kg/m 3  will provide a protective effect against  Poria placenta  (under the conditions of this test).  
         [0109]     The results shown in Table XX do not allow a toxic threshold to be extablished for TBBS. However, based on findings for  Coniophora puteana  (see section 3.2) it is likely to lie somewhere between 0.8 and 7.9 kg/m 3 .  
         [0110]     Overall results for  Poria placenta  can be summarised as follows: 
        TBBF: Protective Effect=0.8-7.7 kg/m 3  (=&gt;0.1-1.0%)     TBBE: Protective Effect=0.8-8.3 kg/m 3  (=&gt;0.1-1.0%)     TBBZ: Protective Effect=0.8-5.9 kg/m 3  (=&gt;0.1-1.0%)     TBBS: Protective Effect=0.8-7.9 kg/m 3  (=&gt;0.1-1.0%)        
 
       Example 6  
     Wood Decay Test (Modified AWPA E7-01)  
       [0115]     The preservative value of TBBA in terms of preventing wood decay was examined by ground contact exposure of TBBA treated stakes at a test plot in Gainesville, Fla. The test detail was essentially based on the “STANDARD METHOD OF EVALUATING WOOD PRESERVATIVES BY FIELD TESTS WITH STAKES”, Standard E7-01, promulgated by the American Wood Preservers Association (AWPA).  
         [0116]     All the test stakes were of southern pine sapwood and were vacuum impregnated with TBBA. The TBBA was dissolved in one of four solutions: ethanol, P9 type A oil, and in two micro-emulsions: 
        emulsion #1: TBBA 20.81%, Butyl Lactate 31.02%, NP-15 22.33% and water 25.83%     emulsion #2: TBBA 20.05%, Butyl Lactate 29.88%, NP-15 21.51% and water 28.55%        
 
         [0119]     Each of the emulsions was diluted so that the corresponding concentration (w/v) of TBBA in all of the solutions was: 1.72%, 3.4%, 5.1%, 6.8% and 8.5%.  
         [0120]     Two groups of control stakes were also installed in the test plot. One group was vacuum impregnated with pure ethanol. The second group was untreated.  
         [0121]     The groups of stakes for each treatment were installed in the test plot, left for seven months, and evaluated according to the procedure set-out in AWPA Standard E7-01. The Standard assigns decay grades, based on an evaluation made at the location of the most extensive degradation of the cross section of the stake, defined as follows: 
        Grade No. 10: Sound, even though there is a suspicion of decay     Grade No. 9: Trace decay to 3% of cross section     Grade No. 8: Decay from 3 to 10% of cross section     Grade No. 7: Decay from 10 to 30% of cross section     Grade No. 6: Decay from 30 to 50% of cross section     Grade No. 4: Decay from 50 to 75% of cross section     Failure        
 
         [0129]     Table XXIII lists the decay ratings for each group of 10 stakes. The concentration of the active ingredient (AI) TBBA for each group of stakes is listed in units of pounds per cubit foot (PCF.  
         [0130]     As can be seen, the group treated with pure ethanol has only 5 instances of Grade No. 10, while the addition of TBBA improved the rating to a count of 8-10. With other treatments of TBBA solutions, the rating ranged from 9-10 counts.  
                                                                                                     TABLE XXIII                           TBBA                DECAY RATINGS            TREATMENT   PCF, AI   “10”   “9”   “8”   “7”   “6”   “4”   “0”                    UNTREATED   0.00   0   1   2   0   0   1   6       CONTROLS       ETHANOL CONTROLS   0.00   5   1   0   0   1   1   2       TBBA in ETHANOL   0.50   8   1   0   0   0   0   1       TBBA in ETHANOL   1.00   10   0   0   0   0   0   0       TBBA in ETHANOL   1.50   8   1   0   0   0   0   1       TBBA in ETHANOL   2.00   8   1   0   0   0   0   1       TBBA in ETHANOL   2.50   9   0   0   0   0   0   1       TBBA EMULSION #1   0.50   10   0   0   0   0   0   0       TBBA EMULSION #1   1.00   10   0   0   0   0   0   0       TBBA EMULSION #1   1.50   9   0   0   0   0   0   1       TBBA EMULSION #1   2.00   10   0   0   0   0   0   0       TBBA EMULSION #1   2.50   10   0   0   0   0   0   0       TBBA EMULSION #2   0.50   9   1   0   0   0   0   0       TBBA EMULSION #2   1.00   10   0   0   0   0   0   0       TBBA EMULSION #2   1.50   10   0   0   0   0   0   0       TBBA EMULSION #2   2.00   10   0   0   0   0   0   0       TBBA EMULSION #2   2.50   10   0   0   0   0   0   0       TBBA in P9 TYPE A OIL   0.25   9   1   0   0   0   0   0       TBBA in P9 TYPE A OIL   0.50   10   0   0   0   0   0   0       TBBA in P9 TYPE A OIL   0.75   10   0   0   0   0   0   0       TBBA in P9 TYPE A OIL   1.00   9   1   0   0   0   0   0       TBBA in P9 TYPE A OIL   1.25   9   1   0   0   0   0   0                  
 
         [0131]     While embodiments of the invention have been described by way of illustration, it will be understood that the invention can be carried out by persons skilled in the art with many modifications, variations and adaptations, without departing from its spirit or exceeding the scope of the claims.